Valley of a thousand caves

[OldGuy]

On my campaign map, I labeled a section the "valley of a thousand caves". I want to create a battle map of a portion of that area and I think I need some suggestions. Every time I've attempted something it just looks like smears (that are supposed to be hills) with dark spots (that are supposed to be cave openings).

I think part of the problem is that I can't locate a decent close-up, top-down image of the type of hills I want, that I can use as an example. Maybe someone has seen something they could link?

I'm visualizing extremely hilly terrain riddled with gullies that twist and turn. The terrain alone restricts vision severely. In the gullies, you can't see past the next turn which is maybe 20' away. On the hill tops you can see other hilltops but not into the gullies so you could be surrounded by all sorts of creatures and not even know it. I'm picturing a damp environment with lots of vegetation and many stagnant pools between the hills (even marsh-like in areas). The gullies are also continually shrouded in fog reducing visibility even further.

I've been working in PS but I think I've given up on my artistic ability. I'm digging out Dundjinni next to see what I can do with that.

I would love some suggestions!
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Honda Rafaga specifications