Calling Geologist climbers in the potomac region

I got to thinking about some of the rock compositions at crags that I climb at and was wondering if there were any rock climber geologists out there who could answer a few questions I had about some decisions I've made about what rock types I'll lead on and what rock types I won't. Specifically I've got questions about what I perceive to be metamorphic rock that's present at Carderock, Great Falls, Little Stony Man etc. I contrast this rock type with the Tuscarora sandstone that I perceive to be present at Buzzards, Sugarloaf, Seneca and Pond Bank. Anybody willing to answer a couple questions with some book learnin' would be much appreciated.

--Wannabe

P.S. Apologies about the double post but I don't really know where the "potomac region" or questions about "Mid Atlantic" climbing belong.

Check out "Flakes, Jugs, & Splitters: A Rock Climbers Guide to Geology" by Sarah Garlick. With the exception of Seneca, it doesn't cover your area, but is still a very good book: Well-written, beautifully illustrated, and informative.

Here is the Rock & Ice review

My buddy Chris is a coastal geomorphologist (specialized geologist, basically) at GMU. Long story short, don't lead at Carderock/Great Falls.

Scott & Jon,
Thanks for the replies. Scott I'll add that to my reading list for sure. Jon-- you definitely know where I'm going with this. It just occurred to me that I don't know anything about the actual rock just anecdotal stuff that people pass on and my own "sense" of what the rock is like. I was hoping to hear about "tensile strength" if you can talk about such a thing with rock. I understand enough about geology to know that certain minerals fracture in certain ways which can have a big impact on how brittle or strong rock is but I don't have information, hard numbers... data. It seems like the book might be the right direction to get started in.

Thanks,
Wannabe

The usgs has geologic maps for google earth...so you can download the .kmz file, navigate to your site, and see what the rock type is (in the opinion of the people who made your map). It's pretty cool.

As to specific properties like tensile strength or general rock integrity: I think the variability in almost any rock type is too great for you to be able to tell from afar if the rock is good or bad enough to climb on. Take any climbing area you know, and you'll see there are some parts of the cliff that are climbable and other parts that are total choss.

You're welcome, Wannabe. Garlick does cover the relative strength (or chossiness) of various types of rock.

Johnny, thanks for the USGS tip. I'll definitely check it out.

Johnny G,
Agreed. I've seen choss everywhere but *if* rock can be considered to be like metal (not a huge stretch in my mind considering both materials are made out of minerals-- but again I'm not a geologist) then properties of the rock could vary greatly depending on its composition. Gold is much softer than iron. Weathering is certainly a consideration but how good a "good" piece of hornblende is as compared to gneiss or sandstone-- that's kinda my question.

--Wannabe