Cross Section C-C'
Cross sections provide another dimension (depth) for looking at the geology of an area. They show what the subsurface distribution of geologic units looks like along a given surface line. Cross-section CC' has some interesting relations. Location C is the southwest corner of the quadrangle map, and C' is the northeast corner of the map. Starting at C' you can see the older river terraces of the Congaree River lying on top of granite, whose surface is decreasing in elevation. The same effect is noticed on cross-section AA' but from the other direction. This is the result of the Congaree River cutting down into the granite and leaving sedimentary fluvial terraces on the edges of the eroded channel. In cross-section CC', granite is completely missing from the section southwest of Congaree Creek. The Geological Survey is still investigating this relation.