Post Lab Assesment 5

If 80 grams of a radioactive isotope starts to decay, how much is left after 4 half lives?

5 grams

Which principle is used to infer that a fault is younger than the rocks it displaces?

Cross-cutting relations

Which time interval is longest?

Eons

Fossils have been around for approximately 20% of Earth's history?

False

The isotope rubidium 87 decays to strontium 87 over a half-life of 48.8 billion years. These isotopes would have experienced nearly one half life in the oldest rocks on Earth.

False

If a radioactive isotope has a half life of 100 million years. What proportion of the radioactive isotope will have been converted to daughter products after 200 million years?

NOT 25%, not 75, not 50

Which principle is used to infer that tilted rocks must have undergone an episode of deformation subsequent to their formation?

Original horizontality

Which event happened first?

Pangea split first

Which of the following are Eons?

Proterozoic Phanerozoic

Which principle is used to infer that rocks toward the bottom of a sequence of layers are older than those near the top?

Superposition

Which represents the longest interval of geologic time?

Time between the appearance of the first bacteria and when oxygen began to accumulate in the atmosphere

Dinosaurs became extinct between the Mesozoic and Cenozoic eras.

True

Which event happened last?

age of dinosaurs

Which event happened first?

age of fishes

The isotope Beryllium-10 decays to Boron-10 over a half-life of 1.5 million years. These isotopes would have experienced nearly three half lives in the oldest rocks on Earth.

false

The isotope Carbon-14 decays to Nitrogen-14 over a half-life of 5730 million years. These isotopes could be used to determine the age of rocks formed early in the Cenozoic Era.

false

The principle of original horizontality states that

sedimentary rocks are formed as horizontal layers.

The isotope Beryllium-10 decays to Boron-10 over a half-life of 1.5 million years. These isotopes would have experienced four half lives in igneous rocks that were 6 million years old.

true

Imagine that North Carolina was submerged by s sudden rise in sea level. New layers of sediment are deposited on the recently submerged land surface. What is the technical name for the surface that lies between the former land surface and the new layers?

unconformity