chapter 7 sections 1, 2 & 3. all deserts have one thing in common… very little rainfall. ...
TRANSCRIPT
Chapter 7Sections 1, 2 & 3
All deserts have one thing in common… very little rainfall.
Rainwater moving through soil carries minerals deeper into the soil through a process called LEACHING
Very little leaching occurs in deserts Upper levels of soil is rich in minerals Not a lot of organic matter = little topsoil
If loose soil is removed, a lower layer of soil, called PAVEMENT is exposed
Pavement is the desert floor The desert floor is made up of hard-baked
sand and/or bare rock particles
Cool Deserts Found on eastern
side of Sierra Nevada and Rocky Mountains
Main plant is the sagebrush
Hot Deserts Found in south
west, particularly Arizona, New Mexico and western Texas
Main plant is the cactus
Desert Climate Rarely get more
than 25 cm of rain per year
Precipitation is the limiting factor of the desert
Most deserts receive less than 10 cm of rain
Hot days and cold nights
Desert Organisms(Plants)
Cactus spines are actually leaves
Cacti are SUCCULENTS, meaning they store water
Aloe vera is also a succulent
Desert Plants cont. Most plants have
shallow roots but some have long roots, like the mesquite tree which has roots 20m deep.
Desert Animals Insects, birds,
reptiles, and mammals
Insects and reptiles have an outer coating to reduce water loss
Most animals are NOCTURNAL meaning they are active at night. Why?
Deserts cover over 30% of Earth’s surface Deserts of the northern belt are found near
the Tropic of Cancer (23ºN) Deserts of the southern belt are found near
the Tropic of Capricorn (23ºS)
Winds move from west to east As they move, moisture is drawn up The newly formed clouds then move up
over the mountains and drop their moisture
The air now is very dry (on the east side), resulting in the formation of a desert OR
A SEMIARID region (not as dry as a desert)
The drying of the eastern side is called the RAINSHADOW EFFECT
The transformation of semiarid land into desert is called DESERTIFICATION
How does this occur?
The Tundra is cold, windy, dry region Tundra is located in Northern Hemisphere in
Alaska, Canada, Greenland, Iceland, Scandinavia and Russia
Takes up 10% of Earth’s Surface Lack of biodiversity makes Tundra unstable
Tundra receives 25cm of precipitation per year
Temp rarely reaches above 10ºC Temperature is limiting factor of Tundra Tundra soil has an ACTIVE ZONE, which may
only be 8cm thick Below that, where the ground never thaws
is the PERMAFROST
Mosses and grasses cover the active zone in the summer
Water cannot drain in Tundra This causes the formation of bogs, marshes,
and small streams This gives mosquitoes and black flies
chances to breed, keeping the food chain intact
Tundra Plants Very small, grow
close to ground
Tundra Animals MIGRATION or
seasonal travel brings in animals
Birds, Arctic Fox, Caribou
Musk oxen, coastal polar bears, and wolverines
Finish Worksheets for Chapter 7