Nourse Farm Surficial Geology (source: Andy Koenigsberg)

Nourse Farm Surficial Geology (source: Andy Koenigsberg)

Station Post Text: In geologic terms, the hill where you are standing is called a “drumlin”.  The name derives from the Gaelic word “drum” which means small hill or ridge. Drumlins are smooth, elongated oval or tear-dropped shaped hills. The long axis of this drumlin, roughly northeast/southwest, is parallel to the path the glacier followed and its blunt end, lying below you to northeast, indicates that the glacier came from that direction. The shape of this drumlin is influenced by underlying bedrock which is exposed on the steep, eastern slope.

Drumlins are composed of very dense glacial till formed as glaciers advanced across the land during the last glacial epoch. Glacial till is composed of ground up bedrock and soil and contains material whose size ranges from flour to large boulders, all compacted together. Till can be as dense as concrete.

The soil on this hill is called “Paxton”, after the Massachusetts town where this type of soil was first described and mapped, in 1922, and mapped throughout New England.  Paxton soils are derived from glacial till which has weathered and softened in the 11,000 years since the last glaciers receded. Unweathered till, often referred to as “hardpan,” is found several feet below the ground surface.

Paxton soils vary in their degree of slope and stoniness. In this spot the soil is defined as “Paxton fine sandy loam”. In contrast, on the other side of the farm, above Jasper Street, it is defined as “Paxton extremely stony fine sandy loam” based on the amount of cobbles and boulders observed at the ground surface.

Paxton soils are well suited to growing agricultural crops, such as sweet corn which is the principal crop in this part of the farm.  In 1991 the Massachusetts legislature designed the Paxton series of soils as the official state soil of Massachusetts.

The patch of rhubarb to your left was planted in 2015.