Geologic History of Earth - Relative Dating Exam
What percentage of parent isotopes remain for a radioactive element that has been through 3 half-lives
12.5%
Scientists infer that early North American humans hunted the mastodon. Carbon-14 dating of the rib bone indicates that 2.4 half-lives have passed since the mastodon was killed. Approximately how many years ago did the mastodon die? (Half-life of Carbon-14 5,730 years)
13,700
How many half-lives have passed if a sample contains 25% of its original carbon-14?
2
The most widely accepted age for Earth is?
4.6 billion years
Which diagram above depicts an angular unconformity?
A
Superposition
A younger sedimentary rock
The extinction of the dinosaurs is attributed to which of the following?
All of them
Which diagram above demonstrates a noncomformity?
C
How do you know that the igneous intrusion is younger than both the layer below it and the layer above it?
Contact metamorphism on both rock layers
The Tyrannosaurus Rex lived during which time period?
Cretaceous
The rock record in outcrop II suggests that an unconformity probably exists in outcrop I between rock units:
D & E
Which sequence represents the relative ages of these rock formations, from oldest to youngest?
D → C → A → B
What is the correct order of geologic time subdivisions from largest amount to smallest amount.
Eon, Era, Period, Epoch
Examination of the fossil record shows a general tendency of organisms to become increasingly more complex through geologic time. This finding supports the theory that living things have undergone
Evolution
Which of the following are qualities of a good index fossil? (Select all that apply)
Geologically widespread, short-lived
Cross-Cutting Relationships
Intrusions or faults that cut across are younger
In Question 4, which geologic principle is best represented by the rock units?
Original horizontality
The greatest mass extinction in Earth's history occurred at the end of which period?
Permian
Lateral Continuity
Rock layers should continue
Intrusions
Rock that is included is older
Original Horizontality
Sediment is deposited in flat
Which type of rock is toughest to radiometrically date?
Sedimentary
The earliest known fossils are called
Stromatolites
Which statement best explains why the volcanic ash layers are useful for correlating the relative ages of the bedrock in the three outcrops?
The ash was deposited over a large area when a volcano erupted
The most widely accepted principle that governs how the earth's surface changes over time
Uniformitarianism which states: the processes today are the same that took place in the geologic past
Why don't all living things become fossils?
because environmental conditions have to be just right to prevent decay
Radioactive carbon-14 is often useful in determining the absolute age of geologic samples because radioactive isotopes:
decay at a constant rate
