The Quarry

The Eli Whitney Armory site is shaped by geology. It sits in a gap between two tall rocky outcrops, Mill Rock and East Rock. The rocks are joined by a much lower ridge - you can notice it just north of the EWMW property, where Whitney Avenue starts up a small hill alongside Lake Whitney. This lower ridge created the natural waterfall on the Mill River that powered the Armory.

East Rock, Mill Rock, and the low gap between them are all part of a much bigger geological feature, the Metacomet Ridge, that runs all the way from the Long Island Sound in Branford to Greenfield in western Massachusetts, less than 10 miles from the Vermont border. The ridge approximately parallels Interstate 91 for much of its length. It is primarily composed of trap rock (volcanic basalt) raised vertically by a tectonic fault.

The stone from this feature was ideal for building, and as New Haven grew, many small-scale quarries sprung up. The Armory was conveniently sited just below a small pinnacle on the northeast side of East Rock. Armory workers quarried stone from below the pinnacle to build sturdy and relatively fire-proof buildings, like the Coal Store. The pinnacle is now part of East Rock Park. You can still see the straight-cut sides of the quarry from the Museum property on the east side of the bridge.

In 1814, Ithiel Town purchased large amounts of stone from the Armory Quarry to build Trinity Church on New Haven Green. In 1861, Eli Whitney Jr. built the Lake Whitney dam using stone from another quarry further along East Rock, on the south side of what is now called Whitney Peak.

Some areas of the Metacomet Ridge are still quarried, but by the 1880s, people had stopped quarrying rock from East Rock and the peak was turned into the park we know today.