Westborough Quartzite Outcrop Area (Arlington)

The oldest rock unit in the Middlesex Fells volcanic-plutonic complex. The type section is in Westborough, Mass., and is well exposed along the Mass Turnpike. Other small outcrops are dispersed throughout the Middlesex Fells. It is the remains of the shores of an long-vanished preCambrian continent. The hard, brittle rock forms a terrace in this region, with a cliff to the east partly buried by the present Forest Street, and covered by Summer Street on the north.