LSAT 132 | Section 1 | Reading Comprehension: Q8

RC Question 8 Explanation

DISCUSSION: We know lichenometry is useful under the following conditions:

• Mountain rocks less than 500 years old.
• Sites should avoid snow avalanches.
• Shade and wind must be factored in.

___________

1. Too old. We should only use lichenometry for sites up to 500 years old. Also, we don’t know if there are mountain rockfalls near this river.
2. Same as A. Also, there are no rocks here.
3. Lichenometry is useful for mountain rocks. There are no mountain rocks at the shore. Also, an “ancient beach” is probably older than 500 years.
4. CORRECT. This has the right factors. It’s in a mountain. And rocks are being exposed. So we can measure how much lichen has grown over the past five centuries. We can figure out when the glacier retreated by checking when lichen started growing – that’s the date rocks were first exposed.
5. The timeframe is right. But lichenometry is for mountain rocks. We don’t know if this is in a valley. Also, lichenometry isn’t useful for identifying rainfall. Instead, rainfall is a confounding factor that must be accounted for.