Earth Science: Average Rate of Sediment Deposition

ssshazam

1. The problem statement, all variables and given/known data

Link of picture that the information below is referring to: http://i56.tinypic.com/283lv.jpg
You encounter the sedimentary rock outcrop shown above while you are out hiking. You collect rock samples from points A-D and go back and measure their ages in your isotope lab.
A=10.1251 million years old
B=10.1259 million years old
C=10.1262 million years old
D=10.1278 million years old
From detailed analyses of the rock textures and minerals found in the rocks, you determine that all of the rocks were formed from sediments deposited in a floodplain environment.

A) Calculate the average rate of sediment deposition for the unit sampled by rocks A and B (show your work and give units):

B) What is the average rate of sediment deposition for the unit sampled by rocks C and D (show your wok and give units):

C) What changes in the local environment do you think might have caused this change in deposition rate?


2. Relevant equations
None that I know of.


3. The attempt at a solution
I don't know how to approach this problem at all.

Thanks

Borek

How is rate of sediment deposition defined?

ssshazam

I'm not sure... that's all the information that's given.

Borek

It should be defined in your books, or in your notes. If it is not - think, what IS rate of sediment deposition?

ssshazam

A) Rock B-Rock A = #
Take that #and 1.8/#
Answer: .00225

B) Rock D-Rock C = #
Take that #and 2/#
Answer: .00125

That's what I think it is.

Borek

0.00225 of what? Fathoms per fortnight? mph? Inches per year?

ssshazam

meter/year

Borek

Now it looks OK.