In a blog post tangentially related to the Reno Park department, a geologist from NOVA took a look at Soapstone Valley, a deep forested gash that divides Forest Hills from Van Ness. I don’t know so much about the science of rocks, but the article is actually really interesting. Soapstone is a very soft stone, consisting of talc that kind of feels smooth but sticky, like soap. Anyway, it’s an interesting article, and the guy has many other posts about DC geology that are also interesting. Have a look.