Fossils of my youth

Inspired by the #GatewayFossil hashtag on Twitter, I’m reposting this piece that I originally published at “Updates from the Paleontology Lab” on June 9, 2009.

My first exposure to fossils in the field (as opposed to in a museum) occurred when I was around 5 years old.

When my father was a teenager he used to hunt with my grandfather in the mountains along the Botetourt-Craig County line in western Virginia, where he had casually noticed some fossils in the stream gravels (I’m not sure he knew at the time what they were). My mother has always had an interest in rocks and fossils (due to the influence of her grandfather), so my dad used to take us up to that area to look for fossils. We mostly found molds of crinoid column segments and occasional brachiopods in a brown sandstone (above). With the limited resources available to a relatively poor child growing up in the country at that time (no internet!), I didn’t know much more about those fossils, and doing my college work in Minnesota and Louisiana I never actually learned much about the rocks I collected in my youth, a point that was emphasized with the discovery last year of the Boxley stromatolite in Bedford County (where I grew up).

Now that I’m back in Virginia with years of geologic training behind me I can look at these rocks in a new light. Last Friday, my father and I spent the day driving around Botetourt and Craig Counties, looking at rocks. Near Webster, VA we stopped at a railroad trestle close to the Blue Ridge Fault, with deformed Cambrian Rome Formation exposed in the trestle foundation:



The concrete used to build the foundation also had large chunks of Conococheague Formation embedded in it (this bridge is only a couple of miles from the Boxley Blue Ridge Quarry):


Moving into Craig County, we followed Stone Coal Road into the mountains (although I’m using the term “road” in its broadest sense):


We came across several roadcuts of interbedded shales and fine-grained sandstones:


These rocks are from the Devonian Chemung Formation (apparently redescribed as the Foreknobs Formation). They are tilted nearly 90 degrees, which is especially clear where the rocks intersect with the road (the lines leading toward the truck):


In a few places the Chemung was rippled:


And eventually we found some examples of the fossil crinoid and brachiopod molds that are common in this unit:


Returning to my father’s house in Botetourt County I took a look at the rocks exposed under his house and storage shed. The exposures are pretty limited:


Even so, there were some interesting bits, including this contact between a cross-bedded sandstone and a limestone:


According to the Geologic Map of Virginia the mountain where Dad’s house is located includes both the Rome and Elbrook Formations (both Cambrian); I think this rock may expose the contact between them (with the Elbrook being the lighter-colored limestone at the top).

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s