Catoctin Creek - Frederick County Maryland

Catoctin Creek road Crossing

  Just west of the town of Jefferson Maryland, routes 340, 180, and Catoctin Creek meet.  The above picture is the road crossing over the creek on 180.  This is a lovely part of Maryland for it's scenic views, gorgeous farmland, and lack of traffic.  Not too far from the Hustle and Bustle of DC is this nicely rural part of the state.  Most people drive past (over) this stream at 60+ mph on 340 and never even know it's there.  Sometimes they are in a hurry to get home, or racing to the nearby casino across the river in WV, but they don't know what they are missing.

  There is a large outcrop in the landscape that causes the stream to divert at this location.  It is a wonderful chance to see how the local rock formations are still at work eroding the valley and hills.

Outcrop causing stream to divert around

 Route 340 was built using this outcrop as a support base for the bridge on both sides of the stream.  Directly north of route 340 the stream meanders through the valley at a low grade and exposes a decent bed and even some minor cliff faces about 150 ft tall.  The stream bed consists mainly of rounded cobbles and gravel with sand interwoven.  The stream itself cuts through the zone of Paleozoic rock formations of either felsic or mafic origin.  Quartz Diorite, Granite, Gabbro, and Serpentinite are all listed as base rocks in this zone.  The stream also pulls from further up county and lies between both Braddock and South Mountains.  Given the location, this creek actually lies between the Blue Ridge Mountains (South Mountain) and and the lowland section of the Piedmont Plateau.  This allows for the erosion of Cambrian - Pre-Cambrian metamorphic to be included in the mix as well.

Catoctin Creek bed

  Given that my visit to this location was the day after spraining my ankle, I was unable to really examine the stream bed.  I did notice some serpentinite samples s well as numerous quartz pebbles while there.  A further and closer examination is definitely warranted.  Catoctin Creek in it's lower reaches has been known to produce some very nice quartz cobbles with crystal formations inside.  Smoky, Milky, Clear, and Blue Quartz are all native to the region.

Close up of stream pebbles

  The last thing of note for this particular spot is the fresh fractured sections of the outcrop that can be found in the stream bed.  As active erosion digs further and further into the cliff, more and more material is washing into the stream.  Given the lack of change in topography at the stream level, most erosion happens during flood stage.  This allows for a greater diversity of mixed rocks in the bed and makes for interesting searching.