Looks like a concrete foundation. Now that I think of it, the majority of cracks happened during a relatively short period of time, and may speak to the drought we had in CO over a period of several years.
I don't think Bentonite is a major element in my neighborhood, and no closed mines either. But I have been told we have expansive soil.
Good point about the downspouts. I have addressed those in years past, but we've had so little rain I don't think it'd matter anyway.
I'll work on getting an engineer to look at it. Thanx much for the help.