Clue's to Earth Past

Fossil
remains, imprints, or traces of prehistoric organism

permineralized remains
fossil in which the spaces inside are filled with minerals

carbon film
thin film of carbon residue preserved as fossil.

mold
cavity in a rock

cast
copy of an original object

index fossil
remains of species that existed on Earth for short periods of time

principle of superposition

states in undisturbed rock layers, the oldest rocks are on the bottom and the young ones nearer the surface

relative age

age of something in comparison to other things

 unconformity
gasps in rock sequences

absolute age
age, in years, of a rock or other object.

radioactive decay
the process of breaking down

half-life
time it takes for half of atoms in the isotope to decay

radiometric dating
processes use to calculate the absolute age of rock

uniformitarianism
the principles states of Earth procceses ocurring today are similar to those occurring today

Water Erosion and Deposition

Runoff
Water that doesn't soak into the ground or evaporate but instead flows across Earth's surface.



Channel
moving water that creates a groove.



Sheet Erosion
occurs when water that is flowing as sheets picks up carries away sediment



Drainage Basin
area of land from which a stream or river collects runoff.

Meander
Broad bend in a stream or river

Groundwater
Water that soaks into the ground through ground pores



Permeable
when water can pass through pores spaces.



impermeable
when water can't pass through ground pores



aquifer
a layer of permeable rock that let water pass freely



water table
upper surface of aquifer

spring
when water table meets a sloping surface and erupts water.

geyser
Hot spring that erupts periodically water and steam into air   

cave
underground opening, that happens when acidic ground water breakdown limestone.

Longshore current
carry metric tons of loose sediments and act like rivers of sand in the ocean

Beach
deposits of sediment parallel to shore.