Question

In a structurally controlled fluvial setting, an asymmetric flight of river terraces T1, T2, and T3 shown in the figure was sampled at location L1. The age of the sample at L1 was 30 ka (kiloyears). Assuming that the terraces were formed entirely due to deformation-related uplift, the average uplift rate in the past 30 ka in the region was ________ mm/yr. (Answer in integer.) 

Hint:

Uplift rate (mm/yr) = \(\frac{\text{Height (m)} \times 1000}{\text{Age (years)}}\). Always convert meters to millimeters for consistency.

Answer 1

Correct Answer: 10

Step 1: Given data.
Elevation difference between L1 and present river level = \(400 - 100 = 300 \, \text{m}\). Age = 30 ka = 30,000 years.
Step 2: Compute uplift rate.
\[ \text{Uplift rate} = \frac{\text{Elevation difference}}{\text{Time}} \] \[ = \frac{300 \times 1000}{30000} = 10 \, \text{mm/yr.} \] Step 3: Conclusion.
Average uplift rate = 10 mm/yr.