Roadcuts of Geologic Interest: I-20

One of three interstate highways intersecting in Atlanta, I-20 traverses Georgia west-to-east from Alabama to South Carolina. In these three states, I-20 encounters all three geologic provinces of the southeast. A few interesting roadcuts:

Douglasville area (west of Atlanta)

Numerous roadcuts both eastbound and westbound show exposures of Austell Gneiss and Bill Arp formation:

• I-20 WB entrance ramp from Ga. Hwy. 5 -- Bill Arp formation
• I-20 WB at North County Line Road -- massive Austell gneiss
• I-20 WB about 3/4 mi. east of Post Road -- megacrystic Austell gneiss
• Left (median) side of I-20 EB about 1 mi. east of Post Road -- contact between Austell gneiss and Bill Arp formation, with many xenoliths

WB approaching Anniston, Alabama

Descending toward the Great Valley, about 1 mile east of U.S. 431 (Exit 191), a cut bank on right exposes wavy phyllite. The last I-20 Piedmont roadcut.