Question

If the basalt at the top of the ancient valley below Vulcan's Throne yields a radiometric date (K-Ar) of 15,000 years, and the lowermost flows in the same valley yield an age of 1.2 million years, what is the rate of basalt filling in the valley in feet per million years (ft/my).

Answer 1

Answer:

$1.69\times 10^3$feet/million year

Step-by-step explanation:

We are given that

Elevation of top of basalt in valley =4100 feet

Elevation of bottom of basalt in valley =2100 feet

Age of top of basalt in valley=15000 years

Age of bottom of basalt in valley=1.2 million years=$1.2\times 10^6 years=1200000 years$

We have to find the rate of basalt filling in the valley in feet per million yeas

Rate of basalt filling in the valley=$\frac{Elevation\;of\;top\;of\;basalt\;in\;valley-elevation\;of\;bottom\;of\;basalt\;in\;valley}{age\;of\;bottom\;of\;basalt\;in\;valley-age\;of\;top\;of\;basalt\;in\;valley}$

Rate of basalt filling in the valley=$\frac{4100-2100}{1200000-15000}=\frac{2000}{1185000}=1.69\times 10^{-3} feet/year$

Rate of basalt filling in the valley=$1.69\times 10^{-3}\times 10^{6}=1.69\times 10^3$feet/million year

Answer 2

The rate of basalt filling in the valley is 1687.76 feet per million years

From the complete question, we have the following parameters are:

• Elevation of top of basalt in valley (H1) = 4100 feet
• Elevation of bottom of basalt in valley (H2) = 2100 feet
• Age of top of basalt in valley (A1) = 15000 years
• Age of bottom of basalt in valley (A2) = 1.2 million years

The rate of basalt filling in the valley in feet per million years is calculated as:

$Rate = \frac{\Delta Elevation}{\Delta Age}$

So, we have:

$Rate = \frac{4100 - 2100}{1.2\ million - 15000}$

Evaluate the differences

$Rate = \frac{2000}{1185000}$

Express as per million

$Rate = \frac{2000}{1.185}$

Evaluate the quotient

Rate = 1687.76 ft per million

Hence, the rate of basalt filling in the valley is 1687.76 feet per million years

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