Rock Cliff Wall in Backyard

[Paul Altman]

Hi

This question is for anyone with experience or knowledge in the area of soil testing/geological surveying.

I am looking at purchasing a home thats built on the side of a hill where they cutout a notch in the hill to build a home in the 60s. The land the house actually sits on is nice big and flat however in the back theres a somewhat sheer cliff wall from the hill being cut out that comes down to the edge of backyard. The closest section of the house to wall is around 20-30 feet away. 

The wall itself is solid rock cliff however you can see where the occasional fist sized chunk had run down and collected at the yards edge. From the bottom to the top the wall is about 15-20 ft with another smaller wall above that that goes to the top of the original hill thats terraced and set further back than the lower wall.

My thoughts are that given that its a rock wall as opposed to dirt, erosion/mudslides etc arent as much a concern, however im not sure the likelihood of the rock its being unstable and possibly crumbling over time.

Any input, advice, or warning are appreciated.

Thanks