Home Geology
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Around 2010, a professor from the College of William and Mary (W&M) showed up at our house and asked if he could walk around our property to do a geological suvey for his student's thesis.  Would we mind?  Of course not!  The result was a publication of a map of the local geology, which I later found on the web.

Our surface formation seems to be "Metagreywacke":

"Metamorphosed sedimentary rock dominated by highly deformed metagreywacke with lesser chlorite schist, biotite schist and phyllite.  Where quartz-rich, metagreywacke appears pinstriped parallel to foliation.  Quartzite is present locally. g, fine-grained, epidote-rich greenstone that occurs in elongate 5- to 10-meter-wide, northeast- and northeast-trending bodies.  Outcrops form discrete ribs exposed in river channels."

Note the mention of greenstone outcrops.  This is the signature rock of the Blue Ridge Mountains.  One of these days, with a GPS, I will take a close look at one or two of the outcrop sites.  So our local rocks are Cambrian (544-505 Ma) to Ordovician (505-438 Ma).  The Arvonia formation is more exposed further to the south, giving rise to the world-renowned slate mines in Buckingham Co.

Gareth Hunt, 28 March 2019

I identified rocks that I had to have jack-hammered to clear my driveway; they are schist (uninspiring fawn color with twinkling crystals of the mineral mica visible) in most cases, but on some the crystals are not so clear, so they might be identified as (the less metamorphosed*) phyllite (per Chuck Bailey, W&M).

Chuck also identified a rock from a stream on my property.  It is water-rounded, but it has skolithos fossils.  He indicated that the only place on the James -- I live on the James -- which has outcrops like that is 150 miles away; it has clearly been washed down from a site in the western Blue Ridge!  We have many examples of these water-rounded rocks.

* metamophosis of shale

shale ->
  slate ->
    phyllite ->
      schist ->
        gneiss

Gareth Hunt, 14 May 2019