Woodfield Reservation rises quite dramatically from the chain of small man-made lakes in the south, at about 160 feet of elevation, to 362 feet on the northern edge, where it is bordered by Drakes Corner Road. This is part of the geological feature know as the Princeton Ridge, formed more than 150 million years ago by a volcanic intrusion of basalt or “diabase” rock in an area largely composed of bedded shale. This basalt rock weathers into large rocky outcrops or boulder fields. Some of the better-known features of the Reservation are two rock formations in its northern upland section: Tent Rock, a massive boulder, and Council Rock, an outcrop overlooking a boulder field.

Several streams cross Woodfield Reservation flowing south into the ponds that empty into Stony Brook. As the rock on the Ridge weathers, it forms a poorly draining clay soil that overlies the better draining rocky soils, creating a patch work of seasonally swampy ground in the south and dry upland to the north.