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Chapter 1 Landforms We begin with two files on physical geography, by which I mean the earth as it would exist without human beings. I begin with landforms because they’re the stage on which everything else plays. And I begin with a bit of geology, because landforms make more sense if you understand the processes creating them. These four maps show the changing position of the continents over the last 250 million years. The earth was already billions of years old at that time, so even the map at the upper left, showing the several continents fused together, shows the earth at a late point in its evolution. About 200 million years ago the supercontinent of Pangaea (“All Earth”) began to split. The name of the northern continent, Laurasia, combines Asia with Laurentian, a name coming from the St. Lawrence River, which drains the Great Lakes and flows past Montreal. The southern continent, Gondwanaland, takes its name from the Gondi, a tribal people living in India. By 145 million years ago, Gondwanaland had broken apart, and the fragment that would become India had detached itself from the other fragments. Sixty-five million years ago, North America was still attached to proto-Europe, but South America had broken free of Africa.

http://pubs.usgs.gov/gip/dynamic/historical.html

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What was driving this movement and continues to drive it today? You might think of the globe as a space-glob of boiling jam, with scum floating about on the top as the hot jam boils below. The bits of scum bump into each other or separate as currents of jam rise from below. It sounds cataclysmic, but the scum in this case consists of crustal rocks moving at roughly the rate at which your fingernails grow. Here's a map showing their movement in the last million years. Red indicates areas spreading apart; blue, areas of convergence. Most of the action is occurring in the oceans, but not all of it, as can be inferred from the volcanism near the west coasts of both North and South America, in Iceland, through East Africa, and from Indonesia to the Philippines, Japan, and back to our west coast.

http://en.wikipedia.org/wiki/Timeline_of_the_development_of_tectonophysics_(after_1952)#mediaviewer/File:Plate_tectonics_map.gif

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New sea floor is being created as the crustal blocks or plates on either side of the spreading centers are pushed apart. In other words, the age of the ocean floor increases as you move away from a spreading center.

http://www.columbia.edu/cu/news/06/08/images/HeezenTharp_900.jpg

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Here's a simplified but ultra-clear map. Some of the plate boundaries mark spreading centers (such as the one through the mid-Atlantic); others mark zones of convergence (such as the one between Australia and the Eurasian Plate).

http://eqseis.geosc.psu.edu/~cammon/HTML/Classes/IntroQuakes/Notes/plate_tect01.html

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What happens when plates collide? The top diagram shows two continents colliding, with one pushed downward. The overriding plate gets crumpled. (A good example is the Himalaya, created by India pushing into Asia.) The lower diagram shows an oceanic plate colliding with a continental plate: in addition to the crumpling, rock from a layer called the lithosphere melts, rises buoyantly, and forms volcanoes. (A good example come from the western edge of Indonesia, where the Australian Plate bumps into the Eurasian Plate.) .

http://walrus.wr.usgs.gov/tsunami/sumatraEQ/tectonics.html http://geomaps.wr.usgs.gov/parks/pltec/converge.html

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The earth has been around long enough to have seen several cycles of plate formation and destruction. For North America, the most recent cycle is shown below in blue and labeled as the Cordillera. The chain continues farther south as the Andes. An older cycle is shown in brown and corresponds chiefly to the Appalachians. Notice that the core of the continent is red or pink. The color distinction is that red indicates continental shields, areas where the exposed rock has not been part of a mountain-building episode since well before the Appalachians. The surfaces here are generally eroded flat, though they may be raised into plateaus. Pink areas are platforms, underlain by the same ancient rock (crystalline basement is the technical term) as the shield but are covered by later rocks formed from sediments deposited when the land was submerged by a shallow sea. The pink and red areas together are called cratons. Oklahoma is part of a platform and therefore it is part of a craton except for a few bits of the Southern Appalachians, locally called the Ouachitas. They look disconnected from the main line of the Appalachians, but that’s because the link connecting them is buried under coastal sediments, shown here as stippled or sandy yellow.

http://home.hiroshima-u.ac.jp/yhiraya/er/Rmin_EG_KS_01_LA%26C.html

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Here’s the global version, with shields in an dusky-orange and platforms in light purple. Areas of more recent mountain building are shown in green. (“More recent” in this case means mountains formed in the last 600 million years.)

https://en.wikipedia.org/wiki/Shield_(geology)

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So much for process: I now begin a survey of landforms, continent by continent. This will occupy the rest of this file. Of all the continents Africa corresponds most closely to its craton: it’s nearly a single block of unbroken ancient rock, exposed in some places as a shield but buried elsewhere by platform rocks. Much of the shield is uplifted in a plateau, especially in the south. To see this plateau, try Google Maps and search Africa. Click on the menu at the left of the search box and choose "terrain." (Here’s a comparison of the normal Google Maps portrait of Ethiopia, followed by the Terrain version.)

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Here’s Africa as shown on the Terrain version. It shows many of the features discussed in the following pages.

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Here's a more conventional map of the continent. It shows the elevated southern part of the continent, where the plateau character is clearly revealed by the shift from green to tan. Fly north from Durban, on the southeastern coast of South Africa, and the pilot may announce, “We’re crossing the Great Escarpment.” He means the edge of the continental plateau. On the map below it’s labeled Drakensberg, meaning “Dragon Mountain.” Don’t ask me why it’s called that! I don’t think anybody knows, except that it’s a name given by the Boers, the early Dutch settlers of South Africa. (“Boer” means “farmer” not only in Dutch but in Afrikaans, which is the tweaked Dutch developed by the Boers in the centuries after their arrival in Africa.)

http://www.ezilon.com/maps/africa-physical-maps.html

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Another version, with the higher areas in pink.

http://dekhasna.com/wp-content/uploads/2013/06/africa-physical-mapsexploring-africa-of8of0te.jpg

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See the plateau eroded on the south into steps? (I went to school with Bill Bowen, the guy who made this map. I think he did a nice job with it.)

http://130.166.124.2/world_atlas/8/files/8-1003-full.html

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Zoom into Lesotho, an independent country surrounded by South Africa. See the eastern boundary of that country?

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Here's a closer peek.

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The plateau surface is to the west of the boundary, in Lesotho itself, and is much dissected by erosion, but if we stand to the east of the boundary and look up, the view is like this. (This picture, like all the pictures in these files, come, with a few noted exceptions, from a ridiculously huge website of my own photos. You can find them, with captions, at greatmirror.com. No need to go there unless you're curious.)

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Here's a view a few miles away but still looking at the plateau:

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And here's a bit of the old plateau that survives as an isolated mesa, just a few miles to the east. The land between the mesa and the plateau has been removed by erosion.

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If you go back to Bill Bowen’s map a few pages ago, you’ll see a canyon cut by a river flowing into the Atlantic. It’s the Orange River, the biggest river in South Africa.

Here’s what the countryside looks like just before the river hits the border with Namibia. It’s dry, flat, and with occasional ridges of rock hard enough to resist weathering. You can see the vegetation sheathing the river (it’s mostly irrigated vineyards for grape, raisin, and wine production), and you can see Upington Airport. At 16,000 feet, its runway is longer than any in the United States. Long story, but South Africa used to be a pariah state, and other African countries refused to allow South African Airways to land on their territory. The company needed a place as far north as possible where its planes could refuel before their long journey north. The problem was that Upington is fairly high and very hot, which meant that loaded 747s needed a super-long runway to get airborne.

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We’re looking over the river. You can just barely make out a patch of water under the darkly shaded mountain. The river here is still on the plateau, but it’s about to take a dive.

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Great view of the bedrock granite. How come there’s no vegetation? Answer: about once a decade the river floods and scrubs everything clean. On the other side of the river you can see some sand left over from a recent flood.

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The main fall. Like all waterfalls, it gradually migrates upstream as it erodes the rock over which it flows. Result: a great view of the bedrock of the continental plateau. By the way, this is Augrabies Falls, and it’s a national park. Worth visiting, I think.

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North of the Equator, elevations are closer to sea level, but every now and then a bit of the old continental core juts up in an erosional remnant like this. It’s Aso Mountain, on the east side of Abuja, Nigeria’s capital. Think you can climb it? I’m betting you can’t, at least not without heavy-duty equipment. (Tough luck: climbing is prohibited anyway.)

Here’s the mountain in Google Earth. At the bottom you can see the small lake that reflects in the photo above.

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Here’s another example. We’re at the foot of the hill fort of Great Zimbabwe.

Unlike Aso Mountain, this hill can be climbed easily.

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Entrance into the fort. Notice there’s no mortar—never has been. There aren’t any doors, either, which implies that the builders, who were here roughly from 1,000 A.D. to 1,500 A.D., felt very secure.

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There’s not a lot to see up top except the plain stone walls of long-vanished rooms, but the quality of stonework is amazing. A few hundred yards away there’s this structure, called the Great Enclosure.

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Inside there’s a solid stone conical tower; no way up or in, and nothing up top. It’s become the symbol of the country of Zimbabwe, even though nobody knows what the tower was for. Some kind of ceremony, presumably. Great Zimbabwe is now on the World Heritage List, and is worth visiting. Few people do, which makes it more fun. (When I was there, I saw maybe 20 Zimbabweans and one white guy, who I teased for being such a chicken that he hired a guide. More fun to get lost, I told him. Besides, you can’t get really lost, only briefly disoriented up on the top of the fort.)

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Often, the old shield is blanketed with windblown sediments, labelled on the map below in yellow as aeolian sediments. That’s the case across much though not all of the Sahara. (The word Sahara means "desert" in Arabic, so combining the name with the word "desert" is silly. People do it anyway, the way they say Sierra Nevada Mountains, meaning Snowy Mountains Mountains.) Note also the bits of the continent in purple. Here volcanoes have cracked the surface, most visibly in Ethiopia but also in lots of other places. Notice, for example, the line of volcanoes in the "elbow" of West Africa (the Gulf of Guinea).

http://rmgsc.cr.usgs.gov/ecosystems/africa.shtml#SL

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That line shows up in this Terrain detail of the mainland and the island called Bioko. (When the Spanish ruled here—they stayed until 1969—it was called Fernando Po.) It's now part of the country of Equatorial Guinea. The map also shows Mount Cameroon on the mainland. It’s an active volcano over 13,000 feet high, and occasionally it has a little snow, even though it’s in the tropics.

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Other volcanic islands lie to the southwest of Bioko. The largest, about 270 miles from Bioko, is São Tome, named for one of the apostles. Which one? Think about it, and you’ll figure it out. (The name is Portuguese because the island was stubbornly held by the Portuguese until 1975.)

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There’s a reason for this line of volcanic islands: Africa is slowly drifting over a hotspot or place of upwelling molten rock. As it does, volcanic material breaks through the surface at different points in the crustal plate. (The same thing is happening elsewhere on the planet. Zoom out from Hawaii and you will see a line of increasingly old volcanoes stretching from the newest, the island of Hawaii, to the oldest, at Midway. Midway is so old and worn down that it no longer looks like a volcano. Most of it is used today as an emergency landing field. It came in very handy when an engine failed in 2014 on United flight 201 from Honolulu to Guam.)

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The Sahara has several old hotspots. They include Ahaggar (or Hoggar) in southern Algeria and Tibesti in northern Chad. Here's a Google snip of Tibesti, showing a bunch of volcanic cones .

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The highest volcano of Africa is Tanzania's Kilimanjaro, which is high enough to have glaciers, though they’re disappearing as the planet warms.

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Vulcanism in Africa is more than a story of hotspots, however. A large volcanic area blankets the Ethiopian Highlands, and everything to the east of this zone will likely break apart from Africa sometime in the next 50 million years. Here's a schematic representation of this rift zone, which sometimes consists of two parallel rifts.

http://www.photomalaysia.com/2014/01/23/ethiopia-the-tree-where-man-was-born/

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Here's a Terrain view of one bit of the Eastern Rift; it includes Kenya’s Kerio Valley National Park.

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How do I know it’s the Eastern Rift? Look at the context. The park is indicated by the red pin, and you can the valley continuing south approximately through Nakuru to Karatu. The Western (or Albertine) Rift is way over to the left and is largely flooded by a chain of lakes. (The name Albertine comes from the northernmost of those lakes, Lake Albert. The lake to its immediate south is Lake Edward. Both names are legacies of Africa’s colonial past. One of these days, I expect both names to change to something Americans will have trouble pronouncing.)

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Here’s a bit of the Albertine Rift up close. Notice the Rwenzori (sometimes spelled Ruwenzoris) and Virunga mountains. They’re frustrating for photographers because they’re so cloudy, but there are volcanoes in the Virungas, along with gorillas. The Rwenzoris (sometimes also called the Mountains of the Moon) are not volcanic but are old shield rocks thrust up in the process of creating the rift valley.

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Here's the general pattern of Africa’s Great Lakes. The longest is Tanganyika, which straddles the border separating DRC (Democratic Republic of the Congo) and Tanzania. Tanganyika is nearly 5,000 feet deep in places. That's triple the depth of Lake Superior, which is why Tanganyika has more water, even though Superior has triple the surface area--37,000 square miles compared to 12,000.

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Search Kalemie on Google Maps and you can see where water leaves Tanganyika and flows into the Congo River.

Farther south, there is another such lake. It's called Lake Malawi by people on its western shore and Lake Nyasa by those on the east. (Nyasa means lake, so calling it Lake Nyasa is like saying "Sahara Desert." Trouble is, if you say, "I went fishing in Nyasa," few Americans will understand you. If you say, "Lake Nyasa," there’s at least a chance they’ll understand.) Search Mangoche for its outlet, which feeds a tributary of the great Zambesi River, which flows to the Indian Ocean. (The tributary is called the Shire, in this case pronounced She-ray.)

https://en.wikipedia.org/wiki/Zambezi#/media/File:Zambezi_river_basin-en.svg

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The Eastern Rift Valley in northern Kenya is occupied by a salt lake called Lake Turkana. It’s salt because rivers bring in trace amounts of salt which accumulate over time because there is no exit except by evaporation.

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Between these two rifts is a broad upland, much of which is flooded by the very large but comparatively shallow Lake Victoria. Maximum depth: less than 300 feet. Think you can see across it? Not a chance. It’s 150 miles across, and if you stand five feet high you can’t see more than about 3 miles on a perfectly smooth sphere the size of the Earth. If you climb a hill 100 feet high, you can see about 12. (The bits of land you can make out here are islands or promontories on this side of the lake. The view is from the north shore.)

https://en.wikipedia.org/wiki/Lake_Victoria#/media/File:Topography_of_Lake_Victoria.png

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The eastern branch of the Great Rift Valley continues north through the Red Sea, which nearly separates Africa from Arabia. The rift continues still farther north between Israel and Jordan, where its deepest part is flooded by the Dead Sea. Still farther north it is flooded by Lake Tiberias (alias the Sea of Galilee and, for Israelis today, Kinneret). Beyond that, it forms Lebanon's famous Bakaa (or Beqaa) Valley, where it appears as a trench between parallel mountain chains. (This is another of Bill Bowen’s maps.)

http://130.166.124.2/world_atlas/5/files/5-1004-full.html

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Here we’re down in the trench and just a few miles north of the Dead Sea. Jericho and the Jordan River (below sea level) are behind us, and Jerusalem is up ahead, elevation about 2,000 feet. (Fifty miles straight ahead, you’re in the Mediterranean.) We’re looking up a canyon, one of several around here that have been the refuge of hermits and monks for many centuries. The building on the right is the Monastery of Saint George.

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“Can you hear me now?” I bet the answer today is yes, assuming the monk has a phone. Does he? Good question. Last time I talked to one of these guys, he was an Australian here as a pilgrim, but that was almost 20 years ago. I don’t think he had one. The massive wall was built for protection against raiding Bedouin. Who built the walls? Mostly Russian pilgrims who were visiting the Holy Land in the 19th Century. I think the place with some updates would make a great B&B, but I’d proceed cautiously because I’ve heard that other monasteries nearby, which allow guests, provide a generous supply of bedbugs. Been there, done that.

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We’ll start moving eastward. Arabia is shown well on Terrain. Geographically, it’s part of Asia, but geologically it’s a separate crustal plate drifting to the northeast, like a raft whose nose or leading edge is being pushed into and under Iran. The southern end of this leading edge is flooded by waters known to us as the Persian Gulf. Understandably, Arabs don’t like that name, but it’s standard in English. The alternative is Arab Gulf or simply The Gulf, although that name will confuse Americans who will probably think instead of the Gulf of Mexico. The highest parts of the Arabian Peninsula are at the back of the tilted raft, especially in western Yemen. But notice the rugged mountains of eastern Oman. They break the pattern I’ve just described. Apparently there’s a reversed fragment tipping westward within the Arabian block.

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Yemen’s mountains are intensely rugged. For example, here's a photo of Aden, at the SW corner of the peninsula. (The dams are of unknown antiquity but were restored about 1900 by the British, whose ships to and from India stopped here for water.)

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That upturned fragment in Oman is pretty interesting. Here’s a picture of it. Super-barren countryside, but somebody once upon a time found a spring and put it to work. Now you know why this is called Jebel Akhdar or Green Mountain. (The picture was taken east of the town of Nizwa, shown on the previous map.)

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As Arabia drifts northeasterly into Asia, it crumples the western edge of that continent. You can see the result in Western Iran and its Zagros Mountains, running the whole length of the country.

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You can see the Zagros here, along with another mountain belt fringing the distant Caspian Sea. Those are the Elburz (or Alburz) Mountains. Notice how the peninsula of Qatar juts into the Gulf like a mitten. Off its western shore is the small island of Bahrain—less than half the size of Oklahoma City. Farther to the right, the Musandam Peninsula of Oman almost makes the Gulf into a lake. The narrow Strait of Hormuz there is a classic chokepoint, one whose closure through act of war would block oil-tanker traffic from the Gulf and create an economic earthquake felt worldwide.

http://130.166.124.2/world_atlas/5/files/5-1012-full.html

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Here, in red, is a view of the oil tankers in the vicinity on July 19, 2019. (Green is cargo vessels, mainly container ships; blue is tugs and “special craft.” Circles indicate ships at anchor.) At its narrowest, the channel is about 20 miles wide, about the same as the English Channel.

https://www.marinetraffic.com/en/ais/home/centerx:56.2/centery:26.2/zoom:11

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Here’s a bit of the Zagros near Tang Panj. (The word tang in Persian means a narrow gorge.) It's a classic case of a fold belt, much like the Appalachians in Pennsylvania. The tangs themselves are a lot like the slot canyons of our own Zion National Park.

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The rivers writhe as they find paths though the parallel folded ridges.

http://en.wikipedia.org/wiki/Karun#mediaviewer/File:Karunrivermapfinal.jpg

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The belt of crumpling continues east through Afghanistan to a mountain cluster or knot in the border-junction area of Tajikistan, Afghanistan, China, and Pakistan. Here the pressure is coming not from Arabia pushing into Asia but from India doing the same thing. The fold belt sweeps east in three bands. The most prominent is the Himalaya, forming a wall in northern India.

http://130.166.124.2/world_atlas/6/files/6-1004-full.html

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Here's a close-up of the Pamirs. The pin is at Gilgit. Funny thing is, I’ve been there but still find the map hopelessly complicated.

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Here’s a simplified view emphasizing the international boundaries.. The dashed lines represent unsurveyed or contested borders. The little arm reaching out from Afghanistan is the Wakhan Corridor, created in the 19th century as a buffer between what were then the Russian and British empires. The pin is still on Gilgit. There’s a road from Islamabad north through Gilgit to Kashgar.

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And here's a photo of the neighborhood. We're on that road in northern Pakistan. The mountains are the Karakoram, a branch of the Himalaya. (The staple food here is apricots, in this photo spread out to dry for storage.)

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Another image, this time with apricots drying on rooftops. In the distance is the huge mountain called Rakaposhi. Its summit is over 25,000 feet above sea level. Can you get there nowadays? I suppose the answer is yes, but you won’t find many other tourists.

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The high point of the Himalaya, as everyone knows, is Mt. Everest. Not everyone knows it’s named after Sir George Everest, who was Surveyor General of India in the 1830s. The image also shows Tibet, most of which is about 15,000 feet above sea level and which is claimed and controlled by China, however much the Tibetans object.

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Everest was first climbed in 1953; since then, it’s become a lot more popular. The season is very short, however, and unpredictable. In 2018 a total of just over 800 people made the summit. The border between Nepal and China touches the peak.

https://www.ft.com/content/501c0180-68d3-11e8-aee1-39f3459514fd

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For $110,000, Furtenbach Adventures guarantees to get you to the top in comfort that pioneer climbers could not imagine. Here’s Furtenbach’s base camp. Preliminary preparations for the four-week trip begin six weeks ahead of time, when the company delivers to the client’s home an oxygen-tent. It isn’t an oxygen-enriched tent; it’s the opposite, to get you used to oxygen deprivation.

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India extends south about 1,500 miles from the Himalaya to Cape Comorin, which nuzzles Sri Lanka. The map shows in green the Indus Valley, now in Pakistan, and the Ganges Valley flowing eastward to its huge delta, shared by India and Bangladesh. If you were to ride a bicycle up the Ganges Valley toward the Indus Valley, you’d never notice the moment when you crossed into the Indus drainage. The map shows a higher strip in light brown, but on the ground it’s all one extensive plain, the Indo-Gangetic Plain. To the south there’s a plateau called the Deccan, meaning simply “the south” in Sanskrit. It’s gently tipped, much like Arabia, so there’s a cliff on the west, while the drainage is almost all eastward.

https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~233998~5509914:South-Asia----Physical-Political

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Another rendition.

http://130.166.124.2/world_atlas/6/files/6-1000-full.html

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New Delhi sits almost at the divide separating the Indus from the Ganges. Farther south, you can pick out the Deccan Plateau and the Western Ghats at its western edge. The map shows Eastern Ghats, but they are much lower. The word ghat, by the way, just means “step.”

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Here's a bit of those “steps” near the town called Mahabaleshwar, a hill station set up by the colonial British to cool off in May, the hot season before the monsoon.)

In case that map isn't dramatic enough, here's a photo from near Mahabaleshwar. Some step. Notice the layer-cake structure. Those are lava flows that solidified about 60 million years ago.

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Neat view?

I didn’t have it to myself!

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Move inland two hundred miles, and the plateau surface is obvious. Rivers have cut channels into the lava flows—and in this case Buddhists about 2,000 years ago excavated cave-temples in one particularly thick lava flow. (It’s a famous place called Ajanta.)

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Here’s part of the cave line-up.

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A cave interior. The wood railing is courtesy of the Archaeological Survey of India. I suppose people otherwise would leave graffiti. Actually, one of the caves has the name of a British soldier who was in the first group of Europeans to find this place. That was in 1819.

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East of the Himalaya, the zone of crumpling bends sharply to the right, crosses western Myanmar (called Burma on this map) and plunges into the sea to form the tiny Andaman and Nicobar Islands. A parallel line to the east forms the long Malay Peninsula. How long? It's about 900 miles from Bangkok (on this map labeled by its Thai name, Krung Thep) to Singapore. Sumatra, the island to the west, is over a thousand miles tip to tip.

http://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~234025~5509915:Southeast-Asia----Physical-Politica

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Here’s a reminder of the plate structure. The Australian Plate is bumping against the big Indonesian islands of Sumatra and Java, part of the Eurasian Plate.

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The Australian Plate pushed under those islands and lifts up their western edge. Some of the rock melts at depth and rises, forming volcanoes. The site of one such volcano is now filled with water and appears on the map as the donut-shaped Lake Toba, about 60 miles along its longer axis and about 1,600 feet deep. Call it the biggest volcanic lake in the world, much larger than Oregon’s Crater Lake.

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One of the greatest eruptions in recorded history occurred in the strait between Java and Sumatra. The volcano blew itself to smithereens. All that’s left is the island cluster labeled here as Pulau Krakatau. The central island, Pulau Anak Krakatau (“Child of Krakatoa” Island) has become dangerously active in its own right.

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Search Merapi and you will see another volcano, this one in the densely settled island of Java.

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Here it is seen from the ground. That’s not a cloud, or at least not a normal cloud. It’s steam coming steadily from the mountain.

From another angle.

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The Pacific Plate is meanwhile pushing north and west, and its leading edge is being subducted or pushed under Asia, which is why the ocean floor has trenches such as the Aleutian Trench south of Alaska. Melting at depth, lava rises in volcanoes forming the Aleutian Islands, stretching in an arc from Southwestern Alaska. Other island chains have been formed, including the Japanese and Philippine archipelagoes. Fujiyama, about 60 miles west of Tokyo, as about as famous as volcanoes get. Another case is Pinatubo, about 60 miles northwest of Manila; it blew up catastrophically in 1991.

http://go.hrw.com/atlas/norm_htm/npacific.htm

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China Proper (roughly the fan-shaped area east of Tibet) is topographically complicated. But notice the extensive area in dark green. This is the North China Plain, which amounts to the valleys of the lower Yellow River and Yangtze. (In China they’re known as the Huang He and Chiang Jiang; the names translate simply as Yellow River and Long River.) Like Iowa, the North China Plain is intensively cultivated; unlike Iowa, it's also extremely densely populated. Similar densities occur around the two lakes you see at the southern end of the plain. They’re called Dongting and Poyang, and their perimeters are densely cultivated, as well as subject to tremendous floods from the Yangtze. In fact, both lakes are overflow basins for that river in the rainy season, so their size fluctuates greatly. The Chinese over several centuries have reclaimed much of the seasonal lakebeds, but the river continues to rise in summer and periodically causes serious floods. See the egg-shaped area shown in light yellow between the North China Plain and Tibet? In English it’s the Red Basin and is the most crowded part of the province of Sichuan, formerly transliterated as Szechwan (a version that survives in restaurants and cookbooks).

https://www.worldmapsonline.com/klett_extra_large_china_physical.htm

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A closer view brings us back to the Pamir Knot at the upper left corner. The Himalaya and Tibet are clear. Fringing Tibet on the north there’s a sister range called the Kunlun. To its north is the Tarim Basin, occupied by the Taklamakan Desert, and north of that basin there’s the Tien Shan, literally the “heavenly mountains.” There’s a big city on the north slope of Tien Shan; it’s Urumchi, population about three million. Call it a reminder that even in China’s empty west there are major settlements. Most of Urumchi’s residents are newcomers from China Proper; they greatly outnumber the original occupants, the Uyghurs.

https://www.mapshop.com/china-physical-map/

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The Tian Shan are high enough to be snowy much of the year. (As photos through airplane windows go, this one isn’t too awful. We’re looking north from the right side of the plane, which was flying from Urumqi to Kashgar.)

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Here’s a version in Chinese. You can pick out many prominent features, including the North China Plain and the Red Basin of Sichuan.

https://www.mapsland.com/maps/asia/china/large-detailed-physical-map-of-china-in-chinese.jpg

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Sichuan was the most populous province of China until its major city, Chongqing, was broken off in 1997 to form a municipality under the direct rule of Beijing. Here’s the Terrain view of the province. Chengdu, the capital, has about five million people and is big enough that United flies there nonstop from San Francisco.

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The Red Basin is the site of China’s most famous irrigation canal, the Dujiangyan Diversion. The cut was originally made about 230 B.C. Water is diverted from the Min River (behind the camera) into a huge canal.

Downstream, the canal irrigates about a million acres. Now you have an idea why Sichuan was historically China’s most populous province.

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To the east and south of the Red Basin, the country is hilly, without a neat pattern of mountain chains.

http://130.166.124.2/world_atlas/7/files/7-1000-full.html

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The most famous part of this hill country is Guilin, of which these two photos give some idea. (Those buckets have "night-soil," as it's politely called in English. I was on a bicycle and didn’t have to look to see was in the buckets.)

Nearby, a waterwheel lifts water into an irrigation channel. Since China opened up to foreigners, this has become tourist country, drawn by the limestone towers and the rice paddies.

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Caves are a common feature of limestone country. Here, near the town of Zhenxiong, a river disappears into White Water Cave. Local boys told me that it emerged ten miles downstream. They had passed through it, they said. I believed them, but maybe they were pulling my leg. Anyway, I wasn’t going to try. No way.

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Here’s another glimpse of the southern hills, this time away from limestone and with unirrigated corn growing at about 6,000 feet above sea level. It’s green but very poor.

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By convention, Asia is separated from Europe by the Ural Mountains, the Ural River, the Caucasus, and the channel leading from the Black Sea to the Mediterranean. The Urals run almost perfectly north-south for about a thousand miles. To their east the most prominent features are the West Siberian Lowland (in green), Lake Baikal at the southern end of the Central Siberian Plateau, and the rim of mountains that extend east, with varying names, from Baikal all the way to the Bering Sea.

https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~231222~5508513:Eastern-Europe-&-Northern-Asia----P?sort=Pub_List_No_InitialSort%2CPub_Date%2CPub_List_No%2CSeries_No&qvq=w4s:/what%2FWall%2BMap%2Fwhere%2FChina;sort:Pub_List_No_InitialSort%2CPub_Date%2CPub_List_No%2CSeries_No;lc:RUMSEY~8~1&mi=1&trs=11

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The Urals are more like hills than mountains, and the West Siberian Lowland extends east more than five hundred miles to the Central Siberian Plateau, which rises gradually toward the north.

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Lake Baikal is about 400 miles long and has a maximum depth greater than a mile. Why so deep? Same story as Lake Tanganyika: this is a rift zone. Baikal has more water than any other lake on the planet unless you count the Caspian Sea, which is salt. Here’s a map showing the faults between which the earth has dropped as the land to either side of Baikal separates. The elevation of Baikal is about 1,500 feet, so most of the water is below sea level. We’ve already seen another rift-valley lake that's entirely below sea level. It's the Dead Sea, of course, salty because it has no outlet. Baikal’s outlet, near the city of Irkutsk, is the Angara River, which flows north to the Arctic Ocean. (Most Americans have never heard of Irkutsk for the good reason that most Americans have never taken a decent geography class. But Irkutsk isn’t a remote village. It has about 600,000 people and is famously proud of its Okhlopkov theater, which opened in 1897 with a play by Gogol.)

http://www.nature.com/nature/journal/v457/n7231/fig_tab/nature07688_F1.html

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Here’s a view from Baikal northeasterly to the Lena River and the mountains beyond.

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The mountains have names, though most are rarely encountered in English. One exception might be the name Kolyma, which often arises when reading about Soviet prison camps and, lately, about melting permafrost.

https://www.britannica.com/place/Siberia

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The Trans-Siberian railroad runs south of Baikal and then south of the Yablonovy Mountains before hugging the Amur River as far as Khabarovsk, where the track heads south to the ice-free port of Vladivostok.

http://transsiberian.info/map.htm

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Though we call it a continent (after all, the British take holidays on “the Continent,” and restaurants often advertise “Continental Cuisine”), Europe is really a Eurasian peninsula shaped like an arrow or spear, with its point in Portugal. From Gibraltar to Moscow, that spear measures about 2,500 miles. One of the curious things about this pseudo-continent is that unless you head into Russia you're never far from the sea. You'll have a hard time finding a spot that's more than 300 miles from salt water.

http://www.zonu.com/fullsize-en/2009-12-22-11443/Europe-physical-map-2006.html

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The old core area is the Baltic Shield, with rocks extending underneath the much larger Russian Platform. The eastern UK, as well as much of France and Germany, are also underlain by the same crystalline basement. An ancient mountain chain is shown in green reaching down western Norway and continuing into the Highlands of Scotland and most of Ireland. (The same chain links up with our Appalachians, but the two halves were pulled apart when the Atlantic opened.) A younger mountain building episode is shown in purple and includes the Urals and several bits of Spain, France, and Germany. Notice the two short brown lines running parallel in Germany. Call it the Rhine Valley, hemmed in by these faults. The youngest system is the Alpine, shown in pink and extending far to the east to include the Himalaya.

http://kids.britannica.com/comptons/art-143546/Tectonic-map-of-Europe

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Here’s a bit of the oldest European mountains. We’re at the very northern tip of the Scandinavian Peninsula, at a place logically called Nordkapp. (I accidentally set my camera to take B&W pictures. I could have kicked myself when I discovered this, too late.)

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Here’s Europe’s part of the Alpine System, including the Pyrennes, Alps proper, the Apennines, the Dinaric Alps, Carpathians, and Balkans. Asia Minor, which is well over ninety percent of Turkey, is part of the system; so are the Atlas Mountains of North Africa. You can see the Rhine heading north through its narrow valley. The hills to its east are the Black Forest, and it is there that the Danube begins. It flows into the Hungarian Basin (here the Plain of Hungary), before cutting through the Iron Gates and reaching another lowland, Walachia or Wallachia, and the Black Sea.

http://www.probertencyclopaedia.com/photolib/maps/Map_of_Europe_(Physical)_1939.htm

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The backward-S curve on the right side of the image traces the Carpathian Mountains in the top limb, the Transylvanian Alps in the middle limb, and the Balkan Mountains on the lower limb. The plains encircled by the S curve are the Hungarian Basin and Wallachia or Walachia. The Danube passes through both, which means that it has to find a way through the mountains.

http://130.166.124.2/world_atlas/4/files/4-1000-full.html

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The pin marks the spot, the Iron Gates.

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Another view of the Alpine System, this time in Europe. Continuing east, it includes the Anatolian Plate, a plateau fringed by the Pontic and Taurus coastal ranges.

http://en.wikipedia.org/wiki/Geology_of_the_Alps

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Here’s the Moroccan bit of the system. The Rif Atlas take their name from a local word meaning “coast.”

https://en.wikipedia.org/wiki/Atlas_Mountains#/media/File:Atlas-Mountains-Labeled-2.jpg

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The High Atlas lie just south of Marrakech (or Marrakesh).

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Here they are, seen looking south from the oasis around Marrakech. The field is fenced with thorns. Nice.

Up top, it’s wet enough for a forest.

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The south side really dries out. Here’s the same High Atlas seen from the Sahara side. This is the Tinerhir Oasis, one of several capturing water flowing south off the mountains.

How’s that for a contrast?

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On the other side of the Strait of Gibraltar, there’s another Sierra Nevada, sometimes confusing to Americans.

At 10,000 feet, they’re above tree line.

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We’ll drift east to the Austrian Alps south of Innsbruck.

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This is very popular hiking country, which explains the sign, which says that entering the meadow is forbidden.

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Italy to the left; Austria to the right. A little grim maybe, but we can blame the clouds and shadows they cast.

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A bit of grass manages to grow close to a glacier. It’s only in the last couple of centuries that this landscape has become popular with tourists. Until then, it was a place to avoid.

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If you come down slope a few miles, the scene turns more hospitable.

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The Pindus Mountains of Greece are almost equally rugged. Here’s the Terrain version of part of them.

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The pin was on Delphi, about a two-hour drive north of Athens.

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Here’s the temple of Pythian Apollo, the site of an important oracle. You remember that Alexander the Great came by and treated the prophetess roughly.

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Bye-bye, Europe. Compared to Eurasia, South America is simple, with shield rocks (in dark mustard) exposed in the eastern half of the continent and with the Andes rimming the west coast. The map adds a third category shown in a light tan and indicating platforms. The sediment carried by the Amazon has over the eons gradually loaded the region sheathing the river so that the shield is depressed along the lower section of the river. In other words, the dark mustard areas north and south of the river are geologically continuous, but their connection is buried. Also, the mustard is the same rock as in the African Shield, to which South America was once attached.

http://pubs.usgs.gov/of/1997/ofr-97-470/OF97-470D/sam06Gmap.html

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A simple physical map highlights the Andes and the old shield areas, identified here as the Guiana and Brazilian Highlands.

http://chsweb.lr.k12.nj.us/gbyrne/worldgeo/notes/chapter13/physicalsa.htm

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The coast around Rio is dotted with shield outcrops a lot like the one we saw earlier at Abuja, in Nigeria. This one is extremely well-known: it’s Sugarloaf. Apologies for the focus; the driver was in a hurry.

Here’s a reminder of the location.

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There are many others nearby, like this rock rising behind the famous Rio slum or favela called Rocinha (“Little Farm”).

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This image gives a good sense of the plateau surface of Brazil, with a sharp edge (the Serra do Mar) close to the sea and tapering to lower elevations farther west.

http://130.166.124.2/world_atlas/3/files/3-1009-full.html

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It’s hard to see the slope, but you can infer it from the pattern of reservoirs along the rivers that flow inland.

Here’s a view just a bit to the south. You can see the sharp edge on the east and a river (well, a series of reservoirs on a river) flowing to the west. We’re here for a feature labelled as Foz do Iguaçu, where the river (the Iguaçu) forms the border with Argentina.

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The countryside here is pretty flat and largely farmed in soybeans.

But you can see the Iguaçu lazily approaching the Foz. “Foz” is Portuguese for “Falls,” in case you didn’t figure that out.

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Here’s the Brazilian side of the waterfall; that big curved section in the distance is called the Devil’s Throat.

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In Portuguese, it’s the Garganta del Diablo.

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The fall extends a long way; that’s the Argentine side on the right. Too bad there’s no audio here; the falls are louder than you would probably guess.

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The plateau here is covered with a layer of lava through which the river has gradually cut back to the east.

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You can go a thousand miles inland and still see rivers running off the western edge of the plateau. Here I’ve traced a 1,200-mile line from Rio to a point in the state of Mato Grosso.

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And here’s a river running at that western point over rapids formed near the western edge of the plateau. The river is called the São Manuel. It’s one of the headwaters of the Tapajos, a major Amazon tributary. The river’s flowing north, toward you in this picture. Those dark boulders are bits of the ancient shield rock.

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Here’s a spectacular topographic display of the shield farther north at the border of Venezuela, Brazil, and Guyana. This is Mt. Roraima, one of the famous tepuis (pronounced te-POO-ees), flat topped but cliff-edged. This one was a popular hike until Venezuela came unglued. For a recent visitor’s account, see https://www.travelsauro.com/hike-mount-roraima-budget/

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And here’s a bit of the famous Argentina pampas, a grassland now heavily farmed but sitting on the southern section of the platform rocks atop the Brazilian shield.

We’re about 70 miles northwest of Buenos Aires.

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Between the Guyana and Brazilian highlands there’s the lowland of the Amazon. We’re about 700 air miles from the Atlantic—or a thousand by the river. Our elevation is about 300 feet above sea level. Big ships can sail all the way up with no problem.

Here’s a location reminder.

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The pin is the highest peak in the Andes (as well as the highest peak in both the Western and Southern Hemispheres). It’s Aconcagua, over 22,000 feet and in Argentina, though only 10 miles or so from Chile.

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You can also see the nearly flat continental shelf and the steep slope to the abyssal sea floor. That deep sea floor is moving into South America and crumpling the edge of the continent to form the Andes.

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Here’s Wikipedia’s encouraging advice if you want to climb the mountain. In mountaineering terms, Aconcagua is technically an easy mountain if approached from the north, via the normal route. Aconcagua is arguably the highest non-technicalmountain in the world, since the northern route does not absolutely require ropes, axes, and pins. Although the effects of altitude are severe (atmospheric pressure is 40% of sea-level at the summit), the use of supplemental oxygen is not common. Altitude sickness will affect most climbers to some extent, depending on the degree of acclimatization.[10] Although the normal climb is technically easy, multiple casualties occur every year on this mountain (in January 2009 alone five climbers died).[citation needed] This is due to the large numbers of climbers who make the attempt and because many climbers underestimate the objective risks of the elevation and of cold weather, which is the real challenge on this mountain. Given the weather conditions close to the summit, cold weather injuries are very common. https://en.wikipedia.org/wiki/Aconcagua#Climbing

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The Andes form a broad, very high plateau in Bolivia. Lake Titicaca, shown here, sits at an elevation over 12,000 feet. It’s fresh, draining into the salt pan you see to the south.

http://130.166.124.2/world_atlas/3/files/3-1014-full.html

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Farther north, in Peru, the plateau narrows, but there are still small pockets of flat land. One is occupied by Cusco, the Inca capital until Pizarro. Looming 60 miles in the distance is Chumpe, 20,000 feet high. If it doesn’t look that high, it may be because Cusco itself is over 10,000 feet above sea level.

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Here’s a tour operator who figures that the tourist fear of altitude sickness is an opportunity. Yes, visitors get out of breath sooner than usual, but unless you have serious health problems walking around at 10,000 feet isn’t a big deal.

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Farther north, in Colombia, the chain splits into the Sierras Occidental, Central, and Oriental. The eastern one splits again, and its arms enclose the brackish inlet called Lake Maracaibo. Notice that there's a detached mountain block just west of there. This is the Sierra Nevada de Santa Marta, which within 25 miles of the sea rises about 18,000 feet. Call it the world's highest coastal mountain.

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The glaciers on that mountain are melting, and less and less snow is falling.

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Home at last. The continental shield, centered on Hudson’s Bay, is shown in various shades of red and pink. To its south the continental platform is shown in pinkish brown--the darker the tint, the thicker the sedimentary cover. That dark patch in Oklahoma is the Anadarko Basin, much explored by the oil and gas industry. The Gulf and Atlantic coasts are shown in gray and indicate more recent areas of marine deposition.

http://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~234477~5510047:North-America----Tectonics

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The Superior Upland is the only bit of the continental shield in the United States. Fringing it are the flat lands of the Central Lowlands, corresponding to the continental platform). The Appalachians extend from Canada south into Alabama, then dipping and rising again to form the Ouachita Mountains. Out West, the Northern Rockies and the Southern Rockies are separated by the Wyoming Basin, chosen by both Interstate 80 and the Union Pacific as the easiest way across the Rockies. You can see the Colorado Plateaus, the Basin-and-Range region, the Columbia Plateaus, and then the Pacific coast mountains, including the Sierra-Cascades. Marked as one thing on this map, they’re really two very different things. The Cascades are volcanoes mostly in Washington and Oregon; the Sierra Nevada is a non-volcanic block in eastern California. The map draws a line separating the Great Plains from the Central Lowlands. It suggests that only the Oklahoma Panhandle is in the Great Plains. On this, there is much disagreement.

http://www.okatlas.org/okatlas/terrain/raisz-natl.htm

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Here’s another interpretation of the Great Plains, on vegetation, not landforms. The dark line demarcates areas that before human settlement were covered in grass rather than trees. The gray line in Oklahoma and Texas demarcates the Cross Timbers, a forested zone just to the east of Norman. The map suggests that the Great Plains extend eastward either to the Cross Timbers of beyond them to another more solidly forested zone. Which is right? There is no absolute answer. There are only several arbitrary choices.

https://www.researchgate.net/publication/334437555_Defining_the_Historical_Northeastern_Forested_Boundary_of_the_Great_Plains_Grasslands_in_the_United_States

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See the Valley and Ridge part of the Appalachians—the purple strip?

http://www.nrcs.usda.gov/Internet/FSE_MEDIA/nrcs143_014530.gif

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Here's Bill Bowen’s map of the same area. At the southern end, the prominent ridge on the east side is the Blue Ridge. Behind it is the Shenandoah Valley. From there on, it’s one ridge after another until you finally climb up to the Allegheny Plateau.

http://130.166.124.2/world_atlas/2/files/2-1048-full.html

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Here's a view centered on State College, home of Penn State. You can see where the name "Valley and Ridge" comes from. It's a classic locale for fold-belt mountains, like the Zagros in Iran. The flatter country at the upper left is the Allegheny Plateau, part of the Appalachian Plateaus.

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The wall of the Alleghenies is the famous Allegheny Front. Here’s a bit of it at Altoona, PA. Notice the Railroaders Museum and, at the Front, a Horseshoe Curve historic monument.

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Here’s a very short video of a double-stacked Norfolk Southern container train climbing up the front. A highways ducks under the track in a tunnel.

https://www.youtube.com/watch?v=5-vkr_Nu2n0

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The Front was a major obstacle to early airline traffic, too, as this monument at Bellefonte recalls.

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Not so much now: I-80 just runs right up the ramp.

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Here's another way of showing the landforms of the U.S. Depending on your travels around the country, you might pick out here the Sierra Nevada, Colorado’s Front Range, the Black Hills, the Ouachitas and Appalachians, the Adirondacks, and lots more.

http://www.codex99.com/cartography/images/raisz/us_lg.jpg

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Here's another version. One big difference between this and the previous map is that this map uses color to show elevation, so you can see the gradual westward rise of the land across the Great Plains. Elevations don't drop again until you hit the West Coast and its green lowlands around Puget Sound in Washington, the Willamette Valley of Oregon, and the Central and Imperial Valleys of California. You'll notice a little orphaned patch of green around Fargo, in eastern North Dakota. It's draining north into Canada, and it's probably the flattest place in the United States.

http://www.lib.utexas.edu/maps/national_atlas_1970/ca000043.jpg

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How did it get so flat? Answer: it's part of the floor of glacial Lake Agassiz, which formed as the continental ice sheet melted about 11,500 years. Silt gradually formed a blanket on its bed. The ice formed a dam ponding the lake, so when the ice went, so did the lake.

http://www.gov.mb.ca/chc/hrb/plaques/plaq1541.html Here’s Louis Agassiz (1807-1873), who basically created the science of glaciology.

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inHere's still another map of U.S. landforms, this one based on satellite measurement and revealing some details. The general flatness of the country is clear, but you can make out the southern High Plains, marked by low cliffs on the east and west. The cliffs are very prominent on I-40 east and west of Amarillo.

http://pubs.usgs.gov/imap/i2206/usa_shade.pdf

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Here’s the highway climbing up from the rolling ranch country to the table-top High Plains surface, indicated by center-pivot sprinklers.

The High Plains edge, or Caprock Escarpment, is especially clear where Palo Duro Canyon has eaten or gullied its way several miles into the flat surface.

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This metal cross at Groom, east of Amarillo on I-40, is a reminder of the High Plains surface.

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Given the slope of the Great Plains, it shouldn’t be a surprise that almost all the rivers across it flow gently eastward. You can make out the Red River here, originating in Palo Duro Canyon and serving as the Oklahoma- Texas border. You can see the Canadian starting in New Mexico, then cutting through the High Plains in a broad canyon before crossing Oklahoma and joining the Arkansas River. The Caprock Escarpment south of Palo Duro Canyon is especially prominent. The High Plains surface is here labelled as the Llano Estacado, a name suggesting stockades, as though the walls of the escarpment resemble the wall of a stockade.

http://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~231095~5508485:United-States----Physical-Landforms

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Drift north a bit and you can see the Arkansas River starting in Colorado, coming through Kansas, then dropping down into Oklahoma to pick up the Cimarron and the Canadian. More streams flow across the Smoky Hills of Kansas and join the Republican River. To its north is the Platte, whose southern branch flows through Denver and which joins the Missouri near Omaha.

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Still farther north, the Niobrara River crosses Nebraska north of the Sand Hills. The Cheyenne River embraces the Black Hills. One river, in the southwest corner of North Dakota, breaks the pattern and flows almost due north through the Badlands before it, too, bends east and joins the Missouri: it’s the Little Missouri. And in eastern Montana you see the Yellowstone River flowing northeasterly to join the Missouri.

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Here it is in summary: the great ramp up to the Rockies.

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Hard to tell that the land is rising straight ahead, but it is, and you know it as soon as I tell you that the view is west in North Dakota. A few miles ahead of us, the plains surface is broken by the north-flowing Little Missouri.

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These are the so-called badlands, but maybe they aren’t so bad. Your call.

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Notice the terrific complexity of the Northern Rockies, straddling Idaho and Montana. There are lots of local names here. The best-known to most Americans are Yellowstone, in the northwestern corner of Wyoming, and just to its south the jagged Grand Tetons. Just south of the Canadian border you can barely decipher the name Glacier Range.

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Here it is a bit closer, with the glacially-carved landscape.

Here’s the view from the southern tip of Lake McDonald.

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And here’s the Wyoming Basin and Southern Rockies. The Front Range, rising west of Denver, are named from the perspective of someone heading west. Farther south, the Sangre de Cristo Mountains are the first mountains encountered by someone heading west through northern New Mexico.

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Nevada is broken up into dozens of parallel ridges and valleys where the earth’s crust has been broken by faults, and the pieces have tilted or slumped. Gradually they've eroded, and the lower part of the blocks have been buried with the eroded material. At the SE corner of the map there are some larger fault blocks. The names are hard to read unless you go to the link, but at the very edge of the map you can make out Death Valley, which is in one of the basins. Which brings us to the Sierra Nevada, which are (or is) the single biggest fault block. One side (on the east) is steep, and the other is gentle. The western half of the block is buried under sediment forming the flat Central Valley.

http://www.yosemite.ca.us/library/geologic_story_of_yosemite/yosemite_country.html

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Dig into that block, or let erosion do it, and you’ll find old granites, famously exposed at Yosemite.

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Ever seen this rock before? There’s a famous photograph of Teddy Roosevelt standing on it next to John Muir. Crazy, if you ask me. Anyway, this was Spring, 2017, when there was a lot more snow and water in the falls than usual.

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Looks like they were there in early summer, after the snow had melted.

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See how the topography changes from the tilted block of the Sierra Nevada to isolated volcanic peaks like Lassen and Mount Shasta? Those isolated peaks keep recurring up to giant Mt. Rainier, south of Seattle.

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Here’s Shasta, not as tremendous as Rainier but at over 14,000 feet not half-bad.

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Here’s Google Terrain’s dramatic rendition of Mt. Rainier.

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It’s often visible on flights to Seattle, even if the surrounding country is clouded over.

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Mustn't overlook Mexico, where (like Bolivia) parallel chains (the Sierra Madre Occidental and Oriental) delimit a plateau, the Mexican Altiplano. The two chains converge in the south as the country narrows.

http://ljhskblair.pbworks.com/w/page/21122341/Physical%20map%20of%20Mexico

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Mexico City, Guadalajara, and Puebla, the country’s biggest cities, all lie toward the southern end of the Altiplano.

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Farther south, the huge North American Plate is pushing against the much smaller Caribbean Plate and creating the chain of volcanic islands called the Lesser Antilles. Some of the eruptions here have been of catastrophic proportions, including the famous eruption of Mt. Pelée on Martinique in the year 1902 and the more recent near-abandonment of the neighboring island of Montserrat caused by the eruption of Mt. Soufriere in 1995.

http://en.wikipedia.org/wiki/File:Caribbean_plate_tectonics-en.png Martinique has the pin; Montserrat is about 150 miles to the north.

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What have we omitted, besides a million details? How about Canada? Here’s a map showing the shield in several shades surrounding Hudson Bay. The platform rocks appear here in light tan (including the SW shore of Hudson Bay). Mountain belts include the Rockies in greens and the Appalachian extension in blues.

http://geogratis.gc.ca/api/en/nrcan-rncan/ess-sst/315e3922-44f8-5c46-b432-72f44d580d76.html

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Here’s the topographic expression of that geology. You might wonder why the shield is depressed here, rather than elevated as it is in Brazil or Africa. The answer is that a million years ago a two-mile-thick continental ice sheet was centered over Hudson Bay, the land surface was depressed by the weight, and has not yet recovered from that load. Notice that the northern edge of the shield was not depressed and forms rugged mountains on the eastern edge of Baffin and Ellesmere Islands.

http://www.nrcan.gc.ca/earth-sciences/geography/atlas-canada/reference-maps/16846#canada

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A reminder of the continent back then. How much weight does a 10,000-foot layer of ice add to the earth’s surface? Ice expands when it freezes so weighs a bit less than water. Still, it’s over 50 pounds per cubic foot, so multiply that by 10,000 and you get a footprint pressing down about half a million pounds per square foot. The basement is solid but only up to a point. It finally yields, and yields most at the center of the ice sheet, where the ice is thickest.

http://www.nature.nps.gov/geology/inventory/publications/reports/acad_gri_rpt_body_print.pdf

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And Australia! It was once joined to Africa and Antarctica. Wedged between it and Africa was what is now the island of Madagascar, about 300 miles east of Africa and more than 80 percent the size of Texas.

http://volcano.oregonstate.edu/book/export/html/138

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Here’s a bit of downtown Sydney. I’m looking at the rock wall. It’s sandstone that originated as sand grains eroded from Antarctica when the two land masses were connected.

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Here’s the most famous bit of scenery in all of Australia. It’s Uluru, in the center of the continent and until recently known in English as Ayers Rock. (Henry Ayers had nothing to do with it—probably never even saw it—so restoring the Aboriginal name makes a lot of sense.) The rock originated in classical platform deposits, with sediments settling on the floor of a shallow sea. In this case, as you plainly see, the rock layers were later tipped almost vertically.

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It’s a funny thing, but if you go up and touch the rock, it’s not at all crumbly. Instead, it feels hard as granite, though it’s a sandstone. I don’t suppose you’ll believe me if I say it almost feels alive.

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Uluru sits in the middle of a plate whose edges are very active. Witness not only the volcanoes of Indonesia but the earthquakes of New Zealand. Here’s Christchurch Cathedral on New Zealand’s South Island. An earthquake did huge damage here in 2011. Repair the cathedral? Knock it down and start over? Residents are bitterly divided on the question.

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Think it’s fog?

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Negative, Captain. Them be steam vents. Plenty of them around Taupo on the North Island.

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Here’s the location. New Zealand is close to a plate margin, which drops off sharply along the boundary.

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That contact is a subduction zone, with the Pacific Plate pushing into the Australian Plate and, along the way, shaking the earth and opening vents to the melted rock below. Beautiful country, but my experience suggests that lots of people there do worry. It might even qualify as PTSD.

http://discovermagazine.com/~/media/Images/Issues/2019/JulAug/EWKplatetectonics2.png