Section 1 earth, science

Geologists

(scientists who study earth) use a model to explain earths structure

Models

Models are used to explain things that cant be fully known or seen

Crust

-covers earths surface
-thinnest layer (5-70km)
-rocks and minerals, fossil fuels
-radiates heat into the atmosphere
-all living things live here

mantle

-2900km thick
-the upper mantle is solid rock
-together the crust and upper mantle are the lithosphere
-the lower mantle is partly liquid

outer core

-2200km thick
-molten (liquid) iron and nickel
-temp 5500C

inner core

-radius 1250km
-solid iron and nickel
-temp 7000C
-high pressure

earthquakes

tremblings or vibrations in the ground.
-the large masses of rock that make up earths surface move very slowly together, apart, and alongside each other/ At these boundaries, pressure builds i[. When the rock breaks, an earthquake occurs

3 types of faults (earthquakes)

1. Normal fault: plates move apart. tension pulls rocks apart

2. Reverse fault: plates move together. compression causes rocks to break

3. Transform fault: Plates move past each other. (shear) rock surfaces get caught and break

technologies for studying earthquakes

-seismographs: detect seismic waves, measuring the strength of quakes. -Earthquakes are given a number on the richter scale based on strength

-geologists observing volcanic eruptions can wear a suit with metal coating that reflects heat.

-a surveyers level can measure changes in the grounds slope (some volcanoes bulge as rising molten rock builds up)

types of seismic waves

-primary waves: come from the focus and are the fastest (move through solids, liquids and gases)

-secondary waves: come from the focus, travel more slowly (pass through solids only)

surface waves: travel out from the epicentre along the surface (slowest, but cause the most damage)

locating an earthquake

because P and S waves travel at different speeds, they can be used to locate the epicentre.

The father apart the P and A waves, the farther away the quake

volcano

an opening in earths crust that releases lava, steam and ash when it erupts.

-volcanoes are erupting, dormant or extinct

volcanoes

volcanoes form where large masses of rock move together.

1. one mass of rock moves under the other.

2. the descending rock reaches hot arena and melts into magma

3. magma rises through cracks

4. pressure builds up at the surface and an eruption occurs

5. lava shoots into the air, flows down and cools into rock (building a mountain)

weathering

when rock breaks down into sediment

erosion

when sediment moves from place to place (by wind, water or ice)

deposition

when sediment is laid down. materials are not lost or gained in these processes

mechanical weathering

when rock is broken down by physical forces, such as water wind and ice

chemical weathering

when chemical reactions cause rocks to change forms. rocks can react with water, chemicals in the water and gases in the air

biological weathering

is the wearing away of rock by living things

sedimentation

-moving water causes weathering and erosion. when it flows quickly, it picks up sediment (rocks, soil and organic matter)

-as water slows, sediment is laid down (called deposition or sedimentation)

fluvial landforms

created by moving water

ex. A flood plain is the land on the sides of a river

ex. A delta is the fan-shaped deposit of sediment at the mouth of river

Moving ice

-A glacier is a moving mass of ice and snow

• as a glacier moves, rocks are picked up and dragged against the land