Unit 4 Vocabulary

Chapter 8

1.) Magma – molten rock

2.) Plate Tectonics – Earth’s lithosphere is divided into plates, most of which are in constant motion.

3.) Tectonic Cycle – the sum of the processes that build up and break down the lithosphere.

4.) Subduction – the process of one plate passing under another plate

5.) Volcano – a vent in Earth’s surface that emits ash, gases, and molten lava.

6.) Divergent Plate Boundary – plates move away from each other

7.) Seafloor Spreading – creates new lithosphere and brings important elements such as copper, lead, and silver to the surface of Earth.

8.) Convergent Plate Boundary – where plates move toward one another and collide

9.) Transform Fault Boundary – when plates move sideways past each other.

10.) Fault – a fracture in rock across which there is movement

11.) Earthquakes – occur when the rocks of the lithosphere rupture unexpectedly along a fault.

12.) Seismic Activity – fault zones where earthquakes are common

13.) Epicenter – the exact point on the surface of the Earth directly above the location where the rock ruptures (focus).

14.) Rock Cycle – the constant formation and destruction of rock.

15.) Fractures – cracks that occur in any kind of rock.

16.) Physical Weathering – the mechanical breakdown or rocks and minerals.

17.) Chemical Weathering – the breakdown of rock and minerals by chemical reactions.

18.) Acid Precipitation – when sulfur dioxide reacts with water vapor in the atmosphere to form sulfuric acid which creates this.

19.) Acid Rain – see acid precipitation

20.) Erosion – the physical removal of rock fragments (sediment, soil, rock, and other particles) from a landscape or ecosystem.

21.) Deposition – the accumulation or depositing of eroded material such as sediment, rock fragments, or soil.

22.) Soil – a mix of geologic and organic components.

23.) Parent Material – the rock material underlying it from which its inorganic components are derived.

24.) Horizons – layers with distinct developed characteristics.

25.) Topsoil – mixed either naturally or by human agricultural practices

26.) Cation Exchange Capacity (CEC) – the ability of a particular soil to absorb and release cations.

27.) Base Saturation – a measure of the proportion of soil bases to soil acids, expressed as a precentage

28.) Soil Degradation – the loss of some or all of the ability of soils to support plant growth.

29.) Crustal Abundance – the average concentration of an element in the crust.

Chapter 9

1.) Aquifers – groundwater exists in the multitude of small spaces found within permeable layers of rock and sediment.

2.) Unconfined Aquifer – water can easily flow in and out of an aquifer

3.) Confined Aquifer – has an impermeable, or confining, layer that impedes water flow to or from the aquifer.

4.) Water Table – the uppermost level at which the water in a given area fully saturates the rock or soil.

5.) Groundwater Recharge – the input process that water from precipitation can percolate through the soil and work its way into an aquifer.

6.) Springs – water from some aquifers naturally percolates up to the ground surface.

7.) Artesian Well – drilling a hole into a confined aquifer releases the pressure on the water, allowing it to burst out of the aquifer and rise up in the well.

8.) Cone of Depression – an area where there is no longer any groundwater, due to the water being rapidly withdrawn

9.) Saltwater Intrusion – with the adjacent salt water is able to infiltrate the area of rapid pumping, making the water in the wells salty.

10.) Floodplain – the excess water spreads onto the land adjacent to the river.

11.) Oligotrophic – lakes that have low productivity due to low amounts of nutrients such as phosphorus and nitrogen in the water.

12.) Mesotrophic – lakes with moderate levels of productivity

13.) Eutrophic – lakes with high levels of productivity.

14.) Impermeable Surfaces – surfaces that do not allow water penetration

15.) Levee – an enlarged bank built up on each side of the river.

16.) Dikes – typically built to prevent ocean waters from flooding adjacent land.

17.) Dam – a barrier that runs across a river or stream to control the flow of water.

18.) Reservoir – water that is stored behind the dam in a large body of water.

19.) Fish Ladders – built like a set of stairs with water flowing over them.

20.) Aquaducts – canals or ditches used to carry water from one location to another.

21.) Desalination – the process of removing the salt from salt water to obtain freshwater.

22.) Hydroponic Agriculture – the cultivation of crop plants under greenhouse conditions with their roots immersed in a nutrient – rich solution, but no soil.