Falling Rocks
Answer: CALDERA
Xiaoyi Yang

In this puzzle, stones are the letters and rocks are the words. You need to search for the words that are rock related. Since the rocks are "falling", everytime you find a rock, you need to remove all letters of the word. If there is a space after removing, the letters above it should be shifted downward to fill the blank. Let the bottom row as the first row and let the left most column as the first column.The location is the first letter's location and move along the specific direction you should be able to find the word, you should be able to find the word. The order of rocks to be removed is:

Word Location (row, col) Direction
ruby (16, 4) down
marble (1, 8) left
sapphire (4, 2) right
coal (4, 2) down
obsidian (3, 8) left
flint (3, 5) right
emerald (2, 7) up
quartz (3, 1) right
pebble (7, 3) down
limestone (2, 9) left
chalk (5, 6) down
gravel (3, 7) left
tuff (2, 4) up
rhyolite (2, 1) right
pumice (1, 5) up
slate (1, 5) right

The last word left is the answer.