Instructions
Draw the straight base line on the paper to indicate the ground level.
Draw the layers of the rock under the ground level by drawing lines that run parallel to the one drawn in Step 1.
Draw a line from the line drawn in step 1 at an angle 45 degrees above the horizontal.
Draw another line that mirrors the line drawn in Step 3. Ensure the tips of the two lines meet in the middle.
Erase the top part of the cone shape created and replace with a horizontally orientated concave line.