Geologic Quadrangle (GQ) maps are multicolor geologic maps on topographic bases in 7 1/2- or 15-minute quadrangle units; scales mainly 1:24,000 or 1:62,500; show bedrock, surficial or engineering geology. Maps are accompanied by brief texts and some maps by structure and columnar sections. GQ's are $7.00 each, plus shipping/handling.

In Massachusetts, not every topographic map has a corresponding published Geologic Quadrangle.