geology exam 2 (1)

plate tectonics

what is plate tectonics?

• the that earth’s lithosphere is divided into moving plates

what is the lithosphere?

• the rigid outer layer of earth made of crust and upper mantle

what drives plate movement?

• convection currents in the mantle

who first noticed continents fit like puzzle pieces?

• Abraham Ortelius

what was Ortelius’s key idea?

• continents were once connected and later separated

who discovered matching fossils across continents?

• Eduard Suess

what is Gondwanaland?

• a southern supercontinent made of connected landmasses

who is the father of continental drift?

• Alfred Wegener

what is continental drift?

• the idea that continents were once joined and later moved apart

what supercontinent did Wegener propose?

Pangaea

what was Wegener’s biggest problem?

• he had no convincing mechanism for movement

who proposed mantle convection?

• Arthur Holmes

why is Holmes important?

• he provided a mechanism for continental movement

who helped developed modern plate tectonics?

• Harry Hess

why was continental drift rejected at first?

• it lacked a mechanism explaining how continents moved

what is continental fit evidence?

• continents fit together like puzzle pieces

what is fossil evidence?

• same fossils found of different continents

why is mesosaurus important?

• it was a freshwater reptile found on seperate continents which proves they were connected

what is rock sequence evidence?

• matching rock layers across continents

what is glacial evidence?

• glacial deposits found in unexpected climates

what is climate evidence?

• fossils found in climates different from where they exist today

what is convection?

• hot material rises, cool material sinks, creating circulation

why does hot material rise?

• it is less dense

why does cool material sink?

• it is more dense

how does convection move plates?

• it drags plates along as mantle material circulates

what are the 3 main plate boundaries?

• divergent, convergent, and transform

what happens at a divergent boundary?

• plates move apart

what is seafloor spreading?

• new crust forms as plates seperate

what is an intracontinental rift?

• a continent splitting apart

what type of rock forms at divergent boundaries?

• basalt

what happens at a convergent boundary?

• plates collide into one another

what is subduction?

• one plate sinks beneath another

• what happens when oceanic plates collide (OC-OC)

• one plate subducts and forms volcanic island arcs

what forms at convergent boundaries?

• trenches and volcanic arcs

what happens at a transform boundary?

• plates slide past each other

what is a mid-ocean ridge?

• an underwater mountain chain where new crust forms

what is a trench?

• a deep ocean feature where subduction occurs

why was WW2 important for plate tectonics?

• it led to ocean floor mapping and sonar technology

continental drift vs plate tectonics?

• continental drift: continents move ( no mechanism)

• plate tectonics: plates move due to convection (complete theory)