Question:medium

Which one of the following is characteristic of a point bar succession?

Show Hint

Point bars typically show an upward transition from fine-grained materials like shale to coarser-grained materials like sandstone.
Updated On: Jun 1, 2026
  • Thick homogenous sandstone
  • Upward gradation from sandstone to shale
  • Upward gradation from shale to sandstone
  • Thick laminated shale
Show Solution

The Correct Option is C

Solution and Explanation

Step 1: Where a point bar forms.
A point bar builds up on the inside bend of a meandering river. The water there slows down as it curves around.

Step 2: How grain size changes.
Near the channel the flow is faster and drops sand. Higher up on the bar, as the river floods and slows, it drops finer mud. So the deposit fines upward.

Step 3: Read the succession from bottom to top.
Reading a point bar from base to top, sand sits low and shale sits high. The question lists the upward order, so we match that pattern.

Step 4: Remove the wrong choices.
A thick plain sandstone or a thick plain shale shows no grading, so both are out. A clean shale to sandstone trend upward also does not match the fining we expect.

Step 5: Final choice.
The choice that matches the fining upward point bar is the shale to sandstone option as listed.
\[ \boxed{\text{Upward gradation from shale to sandstone}} \]
Was this answer helpful?
0