GEOLOGY OF WAKE COUNTY, NC: A VIEW FROM THE GREENWAYS

The City of Raleigh’s Capital Area Greenway System, established in 1974, is one of the oldest systems of its type in the nation, and now comprises 114 miles of interconnected trails that support outdoor activities including walking, running, cycling, and nature study. Proposed expansion of the system would add 120 miles of new trail. Although the current network includes 28 individual trails, most of the miles follow riparian corridors along the Neuse River and two of its major tributaries, Crabtree Creek and Walnut Creek. Most trails have an asphalt surface, and all are well maintained. The system includes loop trails around several flood-control lakes.

The greenway trails provide unparalleled opportunity for bringing geology to the general public. Aspects of fluvial geomorphology and environmental geology are on constant display, but the diverse bedrock geology of Wake County is also accessible to users of the greenways. We have created a blog (ncgreenwaysgeology.blogspot.com) that describes geological features and the related concepts that can be seen and understood along the trails.

From west to east, the county is underlain by: Triassic sedimentary rocks of the early Mesozoic Deep River basin; late Proterozoic to early Paleozoic metamorphic rocks belonging to five separate terranes; and granite of the late Paleozoic Rolesville batholith. The granite can be best viewed along the Neuse River Trail, which runs from Falls Dam SSE for 27.5 miles to the county line, then continues for about five miles in Johnston County. This Neuse River trip begins in metamorphic rocks of the Raleigh terrane, traverses the granitic batholith, and ends in metamorphic rocks of the Spring Hope terrane. Crabtree and Walnut Creeks both run nearly perpendicular to the NNE regional strike, and feed into the Neuse River; the corresponding greenway trails begin in metamorphics and end in granite. Triassic basin exposures may be seen on additional greenways in the Town of Cary.

When written in non-technical language and accessible to the general public via mobile devices, geological guides of greenways, trails and parks provide a convenient mechanism to introduce citizens to the wonder and significance of geology. We encourage their development.