EARTH HISTORY Review Created by Beverley Sutton Pueblo Gardens PreK-8

Our Changing Earth Earth is a geologically active planet. Huge quantities of energy are always acting on the surface of the Earth and its interior. Observable evidence in the present gives information about processes and events that occurred in the past.

How Scientists work: Observation Using one or more of the five senses

How Scientists work: Inference Based on what you already know about footprints and the footprints you see … What happened here?

Layers of the Earth

Let’s take them apart … … and look at them one by one

Crust The outermost “skin” of Earth. Two types: Oceanic crust (thinner, mostly basalt) and Continental crust (thicker, mostly granite)

Lithosphere The crust and the uppermost part of the mantle – brittle and cool

Lithosphere Like the skin and a little of the white of an apple

Mantle Molten rock – between the crust and the core

Core Center of the Earth: Made up of mostly iron and some nickel. Outer core (liquid) Inner Core (solid)

Mineral a crystalline inorganic solid that occurs naturally in the Earth’s crust.

PHYSICAL properties of minerals

Rock inorganic solid that occurs naturally in the Earth’s crust.

Rock Cycle – a process that constantly recycles rock

Rock Cycle

Erosion The wearing away of rocks by weather (wind, water), or chemical means

Sediments small particles of sand, dirt, broken up rocks

Shale Sedimentary Rock Formed by compaction and cementation. Sediments are compacted (packed down) and glued together (cemented). Grains are in layers sandwiched between a muddy matrix Limestone Coal Sandstone

Metamorphic Rocks Rock that was once one type of rock but has changed to another under the influence of heat and pressure. Grains arranged in bands. Marble – which was once limestone Slate – which was once shale Quartzite – which was once sandstone

Igneous Rock rocks that form from magma (melted, liquid rock) that cools and crystallizes. The crystals are randomly arranged and interlocking. Pumice Granite Gabbro

Tectonic Plates Solid plates of lithosphere that float on the mantle

Convection Convection -- Heat transfer in a gas or liquid by the circulation of currents from one region to another.

Divergent Boundary At divergent boundaries new crust is created as plates pull away from each other.

Convergent Boundaries Here crust is destroyed and recycled back into the interior of the Earth as one plate dives under another. These are known as Subduction Zones - mountains and volcanoes are often found where plates converge.

Oceanic-Continental Convergence

Oceanic-Oceanic Convergence

Continental-Continental Convergence

Transform-Fault Boundaries Transform-Fault Boundaries are where two plates are sliding past one another. These are also known as transform boundaries or more commonly as faults.

Fault a crack in the earth's crust resulting from the displacement of one side with respect to the other Strike-slip Fault Normal Fault

Law of Superposition In a sequence of layered rocks, a given bed must be older than any bed on top of it. In other words, each layer is younger than those underneath it.

Law of Original Horizontality Most sediments, when originally formed, were laid down horizontally. In other words, most sediments settle in flat horizontal layers. If the layers are no longer horizontal then something happened to move them.

How landforms change

Seismologist scientist who studies earthquakes

Seismograph an instrument that records the magnitude (size) and duration (how long it lasted) of an earthquake.

Richter scale the logarithmic scale used to measure earthquakes.

Epicenter The point of the earth's surface directly above the focus of an earthquake

Rock Column A diagram that shows the sequence of rocks in a particular area. Stratigraphy – the science of layered rocks.

Index fossil The fossil remains of an organism that lived in a particular geologic age, used to identify or date the rock or rock layer in which it is found. Also called guide fossil.

Our Changing Earth Earth is a geologically active planet. Huge quantities of energy are always acting on the surface of the Earth and its interior. Observable evidence in the present gives information about processes and events that occurred in the past.

Serene, still, and peaceful? Wrong! A dynamic, always changing world!