Geologic time lab

Match the relative dating principles to the best explanation for each of them

-Superposition = younger rock layers are deposited on top of older rock layers -Cross cutting = rock units/faults cutting through are younger -Inclusions = pieces of older rocks may be inside younger rocks -Original Horizontality = sedimentary rocks are typically deposited in flat lying layers -Lateral Continuity = sedimentary rock layers typically cover large geographic distances

If a rock contains 25% parent and 75% daughter of an isotope with a 100 year half life, how old is it?

200 years

If a rock contains 80% Uranium-238, how old is it?

2000 mya

If a rock contains 12.5% of a radioactive parent isotope and 87.5% of the daughter product, how many half lives have elapsed?

3

What percentage of Uranium-238 would the rock contain if it was 4 billion years old?

60%

Based on the above diagram, which order of rock units is correct from oldest to youngest?

DCEGBIJMNLFHKAQal

Relative dating principles allow us to put a numerical age on a rock.

False

Based on the above diagram, which order of rock units is correct from oldest to youngest?

MNOIFECDLBJGAHK

What relative dating principle allows us to say that rock layer B is younger than layer C.

Superposition (Layer B is on top of layer C.)

What type of unconformity exists between E and B?

angular unconformity

What type of unconformity is labelled at C?

angular unconformity

What relative dating principle allows us to say that rock layer E is older than layer D?

cross cutting (Layer D cuts through Layer E.)

Based on the above diagram, which order of rock units is correct from oldest to youngest?

hfeba, granite, cd, dike, g

What type of unconformity exists between D and B?

nonconformity

Based on the above diagram, which order of rock units is correct from oldest to youngest?

sandstone, Fault A, conglomerate, shale, fault B, Batholith, Dike B, Dike A

A half-life is

the amount of time for 50% of the unstable parent isotope to decay