Scapa 7Th Grade Science - Geologic Change Over Time

Front 1

Continental Drift

Back 1

Wegener's hypothesis that all continents were once connected in a single large landmass that broke apart about 200 million years ago and drifted slowly to their current positions

Front 2

Pangaea

Back 2

Supercontinent formed at the end of the Paleozoic Era when sea-level dropped and continents came together to form one giant landmass

Front 3

Crust

Back 3

The solid top layer that makes up the land masses, which we live on, and the ocean floors is called the crust.

Front 4

Mantle

Back 4

Underneath the crust is a thick hot layer of rock that is up to 1,789 miles thick, called the mantle. The top part of the mantle is solid, but scientists believe that 90 miles down the rock is partly melted and flowing.

Front 5

Outer core

Back 5

The third layer of the earth is underneath the mantle, known as the liquid outer core. At about 1,300 miles thick, it is almost entirely made of iron, nickel, and oxygen. The heat is so intense that the metals are molten, and the layer flows very slowly, generating energy that produces the magnetic field of the earth.

Front 6

Inner Core

Back 6

The innermost layer of the earth is called the solid inner core. It is 756 miles across. Although it is the hottest part of our planet at 8,100 degrees Fahrenheit, it is not molten because the pressure is so great. The intense heat is created by radioactive reactions of metals as they slowly break down into simpler forms. It is thought to be a very iron-rich layer.

Front 7

Plate

Back 7

In the theory of plate tectonics, one of the sections of the earth's lithosphere, constantly moving in relation to the other sections.

Front 8

Plate Tectonics

Back 8

Theory that Earth's crust and upper mantle are broken into plates that float and move around on a plastic-like layer of the mantle.

Front 9

Geothermal Energy

Back 9

Geothermal energy is heat from within the earth. We can use the steam and hot water produced inside the earth to heat buildings or generate electricity. Geothermal energy is a renewable energy source because the water is replenished by rainfall and the heat is continuously produced inside the earth.

Front 10

Seafloor Spreading

Back 10

Hess's theory that new seafloor is formed when magma is forced upward toward the surface at mid-ocean ridges

Front 11

Convergent Boundary

Back 11

Convergent plate boundaries are locations where lithospheric plates are moving towards one another. The plate collisions that occur in these areas can produce earthquakes, volcanic activity and crustal deformation.

Front 12

Divergent Boundary

Back 12

Divergent plate boundaries are locations where plates are moving away from one another. This occurs above rising convection currents. The rising current pushes up on the bottom of the lithosphere, lifting it and flowing laterally beneath it. This lateral flow causes the plate material above to be dragged along in the direction of flow.

Front 13

Transform Boundary

Back 13

Transform Plate Boundaries are locations where two plates slide past one another. The fracture zone that forms a transform plate boundary is known as a transform fault. Most transform faults are found in the ocean basin and connect offsets in the mid-ocean ridges.

Front 14

Convection Currents

Back 14

Currents in Earth's mantle that transfer heat in Earth's interior and are the driving force for plate tectonics.

Front 15

Seismology

Back 15

The study of the worldwide distribution of earthquakes over time and the probability of an earthquake occurring in a specific location.

Front 16

Subduction

Back 16

An area at a convergent plate boundary where an oceanic plate is being forced down into the mantle beneath another plate. These can be identified by a zone of progressively deeper earthquakes.

Front 17

Fault

Back 17

Surface along which rocks move when they pass their elastic limit and break.

Front 18

Normal Fault

Back 18

A fault with vertical movement and an inclined fault plane. The block above the fault has moved down relative to the block below the fault.

Front 19

Reverse Fault

Back 19

A fault with vertical movement and an inclined fault plane. The block above the fault has moved upwards relative to the block below the fault.

Front 20

Strike-slip Fault

Back 20

A fault with horizontal displacement, typically caused by shear stress.

Front 21

Lithospheric Plates

Back 21

Large sections of Earth's oceanic or continental crust and rigid upper mantle that move around on the asthenosphere.

Front 22

Asthenosphere

Back 22

plastic-like layer of Earth on which the lithospheric plates float and move

Front 23

Lithosphere

Back 23

Rigid layer of Earth about 100 km thick, made of the crust and a part of the upper mantle

Front 24

Chemical Weathering

Back 24

Occurs when chemical reactions dissolve the minerals in rocks or change them into different minerals.

Front 25

Physical Weathering

Back 25

Occurs when materials such as rock are broken into smaller pieces by physical forces

Front 26

Deposition

Back 26

Dropping of sediments that occurs when an agent of erosion loses its energy and can no longer carry its load.

Front 27

Geology

Back 27

The scientific study of the origin, history, and structure of the earth.

Front 28

Shearing

Back 28

To become deformed by forces tending to produce a shearing strain

Front 29

Hanging Wall

Back 29

The overlying block of a fault having an inclined fault plane.

Front 30

Foot Wall

Back 30

The underlying block of a fault having a declined fault plane.