No answer... the only thing you can do to get pass the monster in gorge is to either kill
it or crush it under the big stone lying on the top of the moutain.

For this, you will need to go to grengar and play the sling game once and then buy some
stones from the merchant.
After this, when you reach the gorge monster, near a point in the mountain, you will see
the cursor change to action. you will be able to throw stones at the small branch holding
the stone which will result in the stone tumbling on the monster.