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Earth's History

*You will leave a space when there are two words in an answer*
Across
A long period in the reduction of temperature indicated by the expansion of ice sheets and glaciers
A calcium mound where lime-secreting bacteria are trapped and contain some of the earliest known fossils
A rock formation that is visible on the surface
The process how some organisms make food from sunlight to create oxygen as a byproduct
Very harmful or disastrous that results in substantial damage
Igneous rock that has crystallized from molten magma
Sedimentary rock's layers
Useful for dating the strata where it is found
The type of age that can be plotted on a calendar.
Igneous rock that has formed from lava
Down
The type of age where the age of a rock is determined by comparing whether it is younger than other material around it.
Widespread and rapid decrease in biodiversity
A very long period of time
This law states that the oldest layer is at the base of the rock and the layers get younger as you ascend
A layer (stratum) of mineral coal
used by scientists to describe the timing and relationships of events in geologic history
Passes through the earth's atmosphere and strikes the ground
Surface contact between two groups of strata
A subdivision of geological time to show when a rock originated
Cross-cutting principle states that the geologic feature which cuts another is the ________ of the two features.