Friday, November 1, 2013

Rocky Branch Trail

The Rocky Branch Trail begins at its intersection with the Walnut Creek Trail, just south of downtown Raleigh, between Fayetteville and S. Wilmington Streets.  It heads northwest, following Rocky Branch through the N.C State University campus, and is connected by a sidewalk along Gorman Street to the beginning of the Reedy Creek Trail at the southeast corner of the Meredith College campus at the intersection of Faircloth and Hillsborough Streets.

Just after crossing Fayetteville Street, at the base of the Mt. Hope Cemetery hill, there is an excellent outcrop of Raleigh gneiss in the creek (Rocky Branch) on the right (Photo).
The banding typical of gneiss is well displayed as alternating dark and light-colored stripes.  In addition, you may see cross-cutting intrusions of light colored granitic rock and dark colored basaltic rock (Photo).
Small folds may also be visible, as well as pot holes scoured by stream erosion.  This outcrop is similar to several other exposures of Raleigh gneiss that can be seen in Pigeon House Branch, on either side of Capital Boulevard just north of downtown Raleigh between Wade Avenue and Wake Forest Road.

After you cross Lake Wheeler Road, the trail passes through grounds of Dorothea Dix Hospital.  There are more outcrops of Raleigh gneiss in the creek, but they are almost completely hidden by vegetation.  The trail passes under a railroad trestle across Western Boulevard from the entrance to Central Prison.  Here, Rocky Branch crosses to the other side of the road, in front of the prison.  There is a very good outcrop of gneiss in the tight bend of the creek over there, but the guards are generally not pleased if you try to look at it.  The outcrop actually has civil-war graffiti carved in it.

If you continue along the south side of Western Boulevard, you get views of Rocky Branch, which has cut a fairly deep valley here.  There are some large exposures of weathered gneiss on the opposite side of the creek, and then there are lots of discarded slabs of pavement obscuring the rocks.  (If you continue uphill and to the left, you can connect to the Walnut Creek Trail via the Centennial Bikeway Connector.  The long hill you climb in that direction, toward Centennial Parkway, testifies to the hardness and resistance to erosion of the next rock unit, Falls leucogneiss.)

Continuing on the Rocky Branch Trail on the north side of Western Boulevard, you pass Pullen Park.  Before reaching the tunnel under Pullen Road and entering the campus of North Carolina State University, you will pass a stream-gauging station operated by the U. S. Geological Survey (Photo).
This station is part of a nation-wide system of 1.5 million sites that measure surface water flow, depth, discharge and other parameters.  The data are collected and sent by satellite telemetry and posted in real time on the website <>.  Information regarding this particular station is located at

After passing through the Pullen Road tunnel, you will come to a large interpretive sign describing the portion of the Rocky Branch Trail that passes through North Carolina State University.  To the right of this sign, and across the trail, there are several ground-water monitoring wells (Photo).
Behind the sign and to the right back in the trees, there are large exposures of Falls leucogneiss, including this one which was the wall of a small quarry at one time (Photo).
 As you pass through the next tunnel (under Morrill Drive), you have crossed the Nutbush Creek fault, which separates the Raleigh terrane from the Crabtree terrane to the west.  This is a right-lateral strike slip fault, meaning that each side moved to the right relative to the other side (i.e. the east side moved south, the west north).  This is the same kind of fault as today's San Andreas in California, except that the Nutbush Creek fault stopped moving about 250 million years ago, while the San Andreas is still active.

As you traverse this portion of the greenway, you will see lots of interpretive markers describing features of streams such as Rocky Branch in a built-up environment.  The big blocks of rock in the creek along here were all hauled in from quarries as part of a stream restoration project.  There is one good place to see an exposure of the native rock, and it is at the intersection of Sullivan Drive and Varsity Drive, adjacent to the baseball stadium and tennis complex.  Here, there is a small waterfall outcrop of Southwest Prong gneiss, a unit within the Crabtree terrane (Photo).
This photo was taken from the culvert beneath the bridge.  To view the rock from above, you may have to lean over the railing along Varsity Drive and peer through the bushes.  Watch out for poison ivy!

Upon reaching Gorman Street, proceed right on the sidewalk to Hillsborough Street, which is the end of the Rocky Branch Trail greenway.  The Reedy Creek Trail greenway begins diagonally across this intersection at the corner of the campus of Meredith College.

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