Geologic Time Scale

Geologic Time Scale
Use with Chapter 14, Section 14.1
Name Date Class
Geologic Time Scale
1. What is the basis of the Geologic Time Scale?
~ The basis of the Geologic Time Scale was when
the geological record was divided into time units
that were related based on the mutual relation of
the rock formations, mostly by the index fossils
they contained.
2. Describe the divisions of the Geologic Time Scale.
~ 1. Precambrian Era
2. Paleozoic Era – Cambrian -Mississippian
- Ordovician -Pennsylvanian
- Silurian
- Devonian
3. During what era and at approximately what date does fossil
evidence suggest life had evolved on Earth? What form of life
was this?
~ During the middle of the Precambrian Era in a period called the
Archaean period fossil evidence suggests that life arose on Earth in
the form of bacteria.
3. Mesozioc
- Triassic
- Jurassic
- Cretaceous
4. Cenozoic
- Tertiary
- Quaternary
4. What forms of living things characterized
the Cambrian period?
~ Invertebrates were the forms of living things
that characterized that Cambrian period.
6. The dinosaurs and many other species became
extinct in a relatively short period of time that
marks what is called the K-T boundary, which
stands between the Cretaceous and Tertiary
periods. About how long ago did the dinosaurs
become extinct?
~ The dinosaurs became extinct around 61 - 66
million years ago.
5. During what era did the first vertebrates
evolve? What were these vertebrates?
~ During the Paleozoic Era the first
vertebrates evolved and they were mainly
algae dominant vertebrates.
7. Imagine you found a fossil of a bird that
dates to 213 million years. Why would this
find be astonishing to scientists?
~ Finding a fossil of a bird that dates back to
213 million years would be astonishing to
scientists because that would be the Triassic
period, the period before the first birds had
8. Suppose a geologist finds a layer of rock that can be dated to
320 million years ago. Layers from which periods would be
expected to be above and below the newly discovered layer?
~ Layers of rock from the periods Pennsylvanian and Mississippian
would be expected to be above and below the newly discovered layer.