Plate Tectonicsand

The Rock Cycle

Three types of plate boundaries

• Divergent plate boundaries– Plates move apart from one another

• Convergent plate boundaries– Internal forces push two plates together

• Transform faults– Plates slide and grind past one another along a fault line

Divergent plate boundaries

Mid-Atlantic Ridge

Convergent plate boundaries

When a tectonic plate sinks, it sinks down into the mantle and becomes very hot. So hot, in fact, that the rock melts. This molten

rock will gradually make its way up to the surface of the earth through a series of cracks. When it reaches the surface of the earth, we refer to it as lava. As layer upon layer of lava builds up, a volcano

is formed.

Transform fault

Convergent and Transform

San Andreas Fault

How much stronger is an earthquake with a magnitude of 9.0 versus an earthquake with a magnitude of 4.0?

9.0 – 4.0 = 5.0

105 = 100000 times stronger

How tsunamis occur

Three types of rock

• Igneous– Granite, lava rock

• Sedimentary– Sandstone, shale, dolomite, limestone, lignite, bituminous coal

• Metamorphic– Anthracite, shale, marble

Igneous rock

Forms below earth’s surface, when molten

rock comes up from the upper mantle, cools, and hardens

Sedimentary rock

Forms from sediments deposited

in layers which accumulate over time – the weight

and pressure “cements” these layers together

Cementation – minerals are precipitated in the pores of sediments, forming cements that bind

sediments and rock

Lithification – the process that converts sediments into solid rock by compaction and

cementation

Metamorphic rock

Forms when preexisting rock is subjected to high

temperatures, high pressures, chemically

active fluids, or a combination of these

agents

Rock cycle

• Interaction of physical and chemical processes

• Recycles the earth three types of rocks

• Slowest of earth’s cyclic processes

• Concentrates the planet’s nonrenewable minerals

• Without it we would not exist

Closure

Why is it important to understand the three major

processes (tectonic cycle, rock cycle, and soil formation) of the

geologic cycle?

Japan Tsunami 2011