Slide 1

Bummer!!!Keep trying!Try to remember what we talked about in class.This is a thinker, no hint available. Think about the forces involved and what keeps them going.

Transform BoundaryTwo plates slide horizontally past each otherReleases massive amounts of energy when plates do finally let goLeads to deformed and fractured crust rather than uplift and subductionCharacterized by long (100 km) fault lines with shallow earthquakes

San Andreas Fault in California is infamous for numerous earthquakes along its boundary

CONTINENTAL DRIFT:Alfred Wegener first supported early mapmakers ideas that the continents fit together like tiny puzzle piecesHis continental drift theory stated that the Earths continents were once all connected in a single landmass called Pangaea, and that when they inevitably split, they continued to drift apart to where they are today.Wegener used the following evidence to support his theories:Similar rock type and ages on different continentsGlacial scaring on continents that are too warm for the existence of glaciers.Coal deposits on continents that are too cold to sustain the environment that would produce coal depositsSimilar fossils found on continents that are separated by vast oceans.Unfortunately, Wegener couldnt explain how the continents moved or what caused their motion, so his ideas were often rejected.

SEAFLOOR SPREADING:Magnetic patterns on the seafloor are symmetric in relation to ocean ridges, indicating that ocean crust on either side of the ridge is moving away from the ridge at essentially the same rateContinual feeding of magma into the ridge causes the ridge to grow, and more seafloor to be producedContinents were just along for the ride, floating on a sheet of moving crustThis concept answered the how question of continental drift, but the why was still a mystery

Sonar and magnetic studies of oceanic rock led to theories of seafloor spreadingNew ocean crust is formed at ocean ridges and destroyed at deep sea trenches

PLATE TECTONICS:The earths crust and rigid upper mantle are broken into enormous slabs called plates (12 major, several minor)Interaction at plate boundaries as they moveContinental Continental ConvergenceWhen neither continental crust will give, plates crash into each otherDue to their relative buoyancy, they are both thrust upward creating folded mountains

Hey!! Nice Mountains!!Mantle ConvectionPut all the previous features together and you have the process for plate tectonics via convection currentsThis is also called CLICK MESlab - PullRidge - Push

Oceanic Oceanic ConvergenceOne plate descends under the other in a process called subductionFeatures formed as the dense basaltic crusts come together are an oceanic trench, an island arc, or a rift valleyThe subducted plate is recycled as it melts again to form magmaThe re-melted magma comes to the surface and cools forming the aforementioned sea volcano and island arc

QUIZ TIME!!!

What is the name of this ancient continent before it broke apart?A) Pancreas

C) PangaeaD) Pluto

B) GondwanalandWhy was glacial evidence and coal bed evidence important for Wegener's theories?A) Coal is an important natural resource, and takes a long time to make.Glaciers havent been around for a long time, so that proves the continents are very old.The existence of coal and glaciers on continents that have opposite climates for them, proves that they have traveled over the years.All of the above

Study the map below and explain why the Pacific seafloor has a larger red area (younger rock) than the Atlantic seafloor?

A) It is hotter.B) More earthquakes, therefore more friction.C) More resistance in the Atlantic basin.D) The seafloor in the Pacific is spreading faster.With the big picture in mind, what plays the biggest part of keeping the movement of the plates going?A) Upwelling or Ridge - PushB) Subduction or Slab PullC) GravityD) All of the choices, or equal forces producing movement