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Chapter 10 Review Questions

Terms in this set (7)

Lithologic: geologists correlate formations between nearby regions based on similarities in rock type
Fossil: correlates units over broad areas, we must rely on fossils to define the relative ages of sedimentary units.
Geologic Columns: By correlating rocks from locality to locality at millions of places around the world, geologists have pieced together a "composite" stratigraphic column. (Represents the entirety of Earth History)
Largest Subdivisions: Hadean, Archean, Proterozoic, & Phanerozoic Eons. (Zoic - means life)
Phanerozoic means "visible life" & Proterozoic means "earlier life"
Archean Eon: The earliest life, bacteria & archea, appeared.
Phanerozoic Eon: organisms w/ hard parts (shells & skeletons) became widespread, so there are abundant fossils from this Eon.
Precambrian time, only small organisms w/ no shells existed (hard to find)
Phanerozoic Eon is subdivided into eras

Oldest to Youngest: Paleozoic (ancient life) Mesozoic (middle life) Cenozoic (recent life)

Divides Further: era into periods into epochs
Geologists now give the age range of fossils species in terms of the periods & epochs of the geologic column, & can use fossils alone to determine the relative age of sedimentary rocks. How to determine Numerical Age
Radiometric Dating: (techniques developed to provide insight into the numerical ages of rocks) These techniques are based on the measurement of radioactive elements in rocks (the science of dating geological materials in years.)
Growth Rings: develop in trees, travertine deposits, and shelly organisms.
Rhythmic Layering: develops in sedimentary accumulations and glacier ice.
Counting rings in trees or layers in sediment
The growth rate of trees
The organic productivity of lakes and seas
The sediment supply carried by rivers
The growth rate of chemically precipitated sedimentary rocks
The growth rate of shell-secreting organisms
The layering in glaciers