Geology

The surface character of this area was determined approximately fourteen to nineteen thousand years ago during the glacial period. At that time the whole valley from Rocky Hill to the source of the Connecticut River in northern New Hampshire was an ancient lake - Lake Hitchcock. As the glacier receded, glacial till (ground-up rock, silt, and clay) was left in deep water.

The river cut down into the valley and raised old river terraces and scultured till ridges. These ridges form the foundation of our main north/south town roads, (East, Main, Hill, Grand and Stone Streets). Pingos - small shallow ponds of open water that become relatively dry in summer - are remnants of the cold, tundra-like permafrost environment. A sand plain was formed in the southern part of town where the Farmington River flowed into Lake Hitchcock. This lake-laid sediment is now found around Stony and Muddy Brooks. In the western part of town, a bedrock of sandstone and silt was formed during the Triassic Period, and basalt ridges of trap rock contain evidence of volcanic material. Basalt was once quarried at the end of Phelps Road where it meets Quarry Road.

Suffield has three types of soil: those deposited by the glacier, those formed by materials deposited by water, and bedrock originating from lava. Because river soils retain moisture and natural fertility, Suffield has excellent soil for cultivating crops. The area is known for early sweet corn, tomatoes, and tobacco, especially shade grown tobacco which has been a cash crop since the turn of the century. Soils in the western part of town are somewhat more acidic and are excellent for nursery stock and turf farming.