CHAPTER 10 Flashcards
in addition to these continents there are large islands such as
- Greenland
- New Zealand
- madagascar
- southeast asian islands
what did Alfred Wegener notice
noticed that the eastern coastline of South America and the western coastline of Africa looked like two connectable puzzle pieces, that the fossils of many ancient animals could be found in both South America and Africa, and that several geologic formations in South America had seemingly identical twins in Africa.
what did Wagner suggest
Wegener suggested that Africa, South America, and possibly other continents had once been connected and had since drifted apart.
what was a hold in wagners evidence?
Wegener could not offer a convincing mechanism for how land masses as big and as seemingly immobile as continents could move
The thickness of the crust varies but is usually between __ and ___ kilo-meters deep
5 and 25
By comparison to the other layers of the earth, the crust is ____
thin
what’s below the crust
the mantle
the mantle
The mantle is a layer over 2,500 kilometers deep. The uppermost portion of the mantle is solid. Along with the crust, this upper solid portion of the mantle is called the lithosphere. Below the lithosphere is a portion of the mantle called the asthenosphere
lithosphere
The lithosphere is the upper portion of the mantle and is not one unbroken layer, but is actually composed of many discrete pieces, or plates, that fit together
asthenosphere
the asthenosphere is viscous, slowly flowing, and its shape may be deformed under the uneven weight of the lithosphere.
what causes the mantle to flow
The intense heat and pressure at great depths causes the solid mantle to behave like a fluid
the core
The core is primarily composed of iron and nickel and is subdivided into the outer core and the inner core
the outer core
outer core is molten liquid
the inner core
the inner core is a solid ball
what does extreme heat of the inner layers of the earth create ?
creates convection currents in the viscous asthenosphere. Lower portions of the asthenosphere slowly heat, expand, rise upwards, and then slowly cool and sink.
what is effected by the currents caused by the heat of the inner layers
Plates, or pieces of the lithosphere
what causes the plates tome slowly ?
The currents pull along the undersurfaces of the lithosphere’s various pieces
what causes the lithosphere plates to slowly sink and melt below the cool curst.
the cool crust is more solid and dense than the layers below it. this occurs gradually along one of the edges of a plate.
how does molten rock escape
As one edge sinks, a small gap is created along the opposite edge, and, through this gap, molten rock is free to escape. This rock then cools, solidifies, and adds its own mass to the edge of the plate. This cycle continues and, ever so slowly, the newly erupted rock will eventually progress to the sinking edged and be melted once more.
plate techtonics
The movement of the lithosphere
how has Plate tectonics been verified
The discovery of mid-ocean ridges revealed plate edges where new crust was being formed. Studies of mid-ocean ridges show that the crustal rocks on either side of the ridges have indeed been slowly drifting apart.
how can we record the speed of moving plates
Advanced global positioning satellites tracking systems can detect the ongoing movements of the continents and even record their speeds.
what are sites for large pressure releases in the form of volcanic activity and earthquakes and gradual pressure releases.
As plates move, they sometimes come into conflict and collide. The boundary where two plates collide
what can these pressure releases do caused by boundaries within collisions ?
they can build mountain ranges.