Hi, making a weathered rock following the reference image below. I want to get dirt pattern-like thingy (circled in red) that spreads downwards from the top of the rock.

In the file attached, i am using Surface Normal in Y fed into the bias of “Blendregion” and attempted to use “Turbnoise” to get some sort of pattern. Appears i could be using it wrongly and haven't achieved what i wanted.

Initially i used color map for the rock but i wanted to try the procedural shader approach that way i don't have to worry about UV.

Hoping to get some guidance here, thank you!

eitht.