You are asked to date a moraine in the Indian Peaks of the Front Range, Colorado, and choose to do so using ¹⁰Be concentrations in moraine boulders. One of the key calculations you have to make in this business is how big a sample to collect. 

a) Using the following constraints, estimate how much sample you will need to collect. Report the answer in kilograms.

The AMS method requires that you provide them 2 million atoms of ¹⁰Be.

 • The moraines are located out in the valley well away from any valley walls that would mask the radiation from cosmic rays.

• We expect the moraines to be last glacial maximum (LGM) in age.

• The rock type is a granite with roughly 30% quartz.

• The elevation at the site is 8236 ft.

• The ¹⁰Be production rate at sea level is 5 atoms per gram of quartz per year.

• The rate of increase of production rate with elevation is an exponential with a length scale of 1.5 km. (in other words, the equation for production rate is , where z* = 1.5 km)

b) If this mass is a cube, what is the length of a side of the cube, in m? In other words, just how big is this?

Transcribed Image Text:

P = P osealevel *e(z/z*)