Lake Chatuge

Ultramafic Rocks

Location

Lake Chatuge is located on the border between  North Carolina and Georgia.  The site location for study was on the Georgia side of the lake on Lower Belle Creek Road behind the Belle Creek Church in Towns County, within the Greenville Quadrangle (fig. 1).  The UTM coordinates for the site location are as follows:

17 248867 E, 3973262 N   

Nick,Jim, and Tiffany in awe of the ultramafics

The Rocks

The ultramafics are an assemblage of deformed and retrograded granulites exposed along the edges of the Shooting Creek Window which runs through the Hayesville Thrust Fault. The ultramafics include minerals such as olivine, plagioclase feldspar, clinopyroxene, chlorite schist, and garnet. The ultramafics are underlain by biotite gneiss country rock and overlain by garnet mica schist (Kieth,1907).  The garnet mica schist is the oldest rock unit of the three.

Garnets are seen throughout the rock

Origin of the Ultramafics

There are 2 theories as to how the ultramafics came to be present at Lake Chatuge

1. The rocks are a sill (Hartley, 1973).  The rocks occur as a tabular unit that tends to parallel the foliation of the country rocks.

2.  The rocks were tectonically emplaced (Kolsrud, 2001).  The rocks started as shallow ocean units that were intruded by underthrusting and subduction to come to rest in the Lake Chatuge area.  Parallel foliations between the ultramafics and the country rock would have been as a result of emplacement preceding or occurring during Taconic activity.

Chuck the Geology Duck gets his photo taken with the ultramafics

Throughout the area the ultramafics are oriented with a very steep dip.  It is on average 75 degrees from horizontal.

Note: Don's leg appears to the north of the ultramafics.

Darlene explains the geology of the area to her fellow classmates.  (Special thanks to Dr. Robert Hatcher for the detailed geologic maps)

Jim and Chuck the Geo-Duck pose with a 400+ pound rock