Computer modeling is a very important function in the earth sciences, enabling scientists to input all types of data to visualize a wide variety of earth processes. Through research like the model below, structural geologists seek to understand the deformation of rock occuring during tectonic processes. Deformation results in folds, faults, and fractures. These structures occur at all scales, from that observed using a microscope to that of an entire mountain, and are important geotechnical considerations for many engineering applications. The full scientific explanation for this model and more links appear below the diagram.
Geology students commonly conduct research as part of their undergraduate curriculum. An example of this is the work of Brad Jackson, a recent graduate of UTC's geology program. Brad researched the structural geology of McLemore Cove in Walker County, Georgia, 40 kilometers (25 miles) south of Chattanooga. Brad presented results of his research at the 2004 meeting of the Geological Society of America in Washington, D.C.
As part of his research, Brad and his research advisor, Dr. Jonathan Mies, produced this illustration of Lookout and Pigeon mountains and the McLemore Cove anticline. Digital elevation models (DEM's) were rendered such that the observer is 10 km south of Dougherty Gap (34.56°N, 85.45°W), 1,500 m above the ground (2,000 m above sea level), and is looking due north. The landscape is based on USGS 30-m DEM data for the Sulphur Springs, Cedar Grove, LaFayette, Valley Head, Dougherty Gap, and Trion 7.5-minute quadrangles. The geology shown in the two cross sections (A-A' and B-B') was modified from that of Charles Cressler (1964, Georgia Geologic Survey IC 29). The DEM of the folded surface was generated with FOLD2DEM software by Dr. Mies. Both DEMs (landscape and folded surface) were rendered using 3DEM software by Richard Horne.
The valley floor of McLemore Cove is more than 400 meters (1,300 feet) below the plateau surface of Lookout and Pigeon mountains. The cove reveals Ordovician through Pennsylvanian sedimentary layers that are dominated by dolostone, limestone, chert, shale, and sandstone. Cliff-forming Pennsylvanian sandstone, at the top of this sequence, resists weathering and forms the plateau surface. The sandstone dips outward, away from the cove, along its upturned rim.
As illustrated here, Pigeon and Lookout mountains are underlain by broad synclines (downward flexures of rock layers, such that resulting folds have low-lying troughs). McLemore Cove is the topographic expression of the intervening anticline (upward flexure, such that the fold has a high-standing crest) that once towered over 2000 meters (6,500 feet) above the level of the present-day valley floor. The McLemore Cove anticline plunges gently to the southwest and is slightly asymmetric, such that its northwest limb is steeper than its southeast limb.
Joints (planar fractures) in and along the rim of McLemore are differentiated by orientation into two sets that are geometrically related to the fold. Cross-fold joints dip steeply to the northeast and are perpendicular to the fold axis, whereas axial joints are parallel to the fold axis. Traces of joints are schematically shown on the folded surface (blue = cross-fold joints, red = axial joints).
The plateau surface of Pigeon and Lookout mountains is drained by a rectangular pattern of streams, linear sections of which coincide with joint orientations. This suggests that joints like those observed in McLemore Cove occur in the adjacent plateau and control the drainage of its surface water. These joints are also likely avenues for subterranean water flow and contribute to the development of caves in the area.
Through research like this, structural geologists seek to understand the deformation of rock, as occurs during tectonic processes. Such deformation results in folds, faults, and fractures. These structures occur at all scales, from that observed using a microscope to that of an entire mountain, and are important geotechnical considerations for many engineering applications.
Dr. Jonathan Miles
Robert Lake Wilson, Associate Professor of Geology
Check out his webpage to download the software to create the above computer model (Mac OS 9 and OS 10 only).
Dr. Miles has also put together several interesting geological outcrops you can visit at: Chattanooga Outcrops.
In conjunction with Dr. Ann Holmes, Dr. Miles also has information on Science workshops for middle school teachers.
Cool Sites to visit:
Geologic Story of the Ocoee River
East Tennessee Geological Society Virtual Field trip
