Vocab
Illustrations
Critical Thinking
100
Good index fossils are often abundant or easily identified. Describe two other characteristics of fossils that makes them good index fossils.
1. They lived for a short period of time
2. They are found over a large geographic area
100
Which is younger, the fault or deposition of shale?
the fault. (Law of Cross-cutting relationships)
100
Which is older -- the basalt or the whole rock (which is conglomerate)?
the basalt is older
200
What is the relative age of a fault that cuts across many rock layers?
- The fault is younger than all the layers it cuts across
- The fault is older than all the layers it cuts across.
The fault is the same age as the top layer it cuts across.
The fault is the same age as the bottom layer it cuts across.
1. The fault is younger than all the layers it cuts across
200
Columns A, B, C, and D below represent outcrops, of the same sequence of bedrock layers, found within 20 miles of each other. The rock layers have not been overturned.
Which surface bedrock is youngest in age?
(1) siltstone (3) limestone
(2) dolostone (4) sandstone
(1) siltstone
200
Which life-form existed on Earth for the shortest period of time?
(1) dinosaurs
(2) ammonoids
(3) placoderm fish
(4) trilobites
(3) placoderm fish