Invictys,

The map looks better with Neyjour's rocks. I advise you to make your own using her idea: get good overhead photos of rock and stone (see attached examples at reduced quality); cut out your desired shapes with a feathered outline & recolour as required; profit! Or even better: cover your image in the rock picture and use a mask to blank it out, than use a fuzzy brush to mask bits of it back in respecting the rock outlines of the rock image. I personally don't like to use heightmaps to create rocks because it gives them an overly metallic (ie high contrast) appearance, however your canyon is so good I think you might be able to pull it off.

Click image for larger version. 

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