Clues to Earth Past

Fossil
are the remains, imprints, or traces of prehistoric organism.

Permineralized remains
are fossils in wich the spaces inside are filled with minerals from groundwater.

Carbon film
A thin film of carbon residue is left forming a silhouette of the ogirginal organism. 

Mold
a cavity in the rock.

Cast
a copy of the original object.

Index fossils
are the remains of species that existed on Earth for relativly short perios of time. 



Relative age
is the age of comparrison to other things

 Unconformity
 gasp in rock sequences.  

Absolute age   
is the age in years of a rock or other object.

Radioctive decay
the process of breaking down.

Half life
of an isotope is the time it takes for half atoms to decay

Radiometric dating
is the total of calculating the ratio of the absolute age of the rock.

Uniformitarianism
 scottish scientist James Houston used it 
      

Surface water

1-runoff:  
water that doesnt soak into the ground or evaporates.  



2-channel:  
water moving down the same path and creates a groove.

3-sheet erosion:
occurs when water is flowing as sheets and oick up sediments.

4-drainage basin:  
is the area of land from wich a stream or river collect runoff.

5-meander:
the curve groved to become a broad arc.

6-groundwater:  
water that soaks into the gorund and collect it in empty spores.

7-permeable:
when water can pass through it.

8-impermeable:
when water cannot pass throguh it.

9-aquifer:
a layer of permeable rock that led water move freely.
 
10-water table:
the upper surface of this zone.

11-spring:
  are found on hills or other places were water table melts.

12-geyser:
is a hot spring that erupt periodically.

13-cave: 
an undergorund opening.

14-longshore current:
water that runs paraller to the shroeline.

15-beaches:  
are deposits of sediment that are paraller to shore.