Best geology...

[Joefish]

A big problem is saving memory. You don't want all your rocks looking the same, but if it's a unique piece of art for the background then that's all your memory gone in just a few screens.

[PROSM]

A big problem is saving memory. You don't want all your rocks looking the same, but if it's a unique piece of art for the background then that's all your memory gone in just a few screens.

I totally agree. Slightly unrelated to geology, but Jonathan Cauldwell's Egghead 6 gets around this by scattering random tiles when building the level surfaces, which makes each section look unique without using too many bytes. My only complaint is that he uses a different RNG seed each time a screen is constructed, which stands out when flipping back to a screen just moments later. I use a similar technique in my game, but with the brick walls, by randomly scattering 'broken' tiles over the brick surface after the original image has been decompressed into the background buffer.

[Cole]

I always quite liked the rocks in the second level of Dynamite Dan II.

[Alessandro]

I would say this background in Yie Ar Kung Fu is something inspired by traditional Japanese art

Chinese. It's called Shan shui, lit. "mountain (and) water". The Japanese imported that style from China (among other things) in the Nara period, ca. 8th century.

[Lethargeek]

cave level of Viaje al Centro de la Tierra:


also 2nd level of Che-man - blocky but good:

[DouglasReynholm]

Perhaps less rock like than some of the other suggestions, but I always liked the 'rocky cores' of the planets of Starquake and Cybernoid.