The Oak Ridges Moraine consists of numerous layers of sedimentary material, for some of which the origin is unknown. The base of the moraine touches bedrock; "it is not clear if the bedrock valley itself was sculpted by a subglacial meltwater event, or was of a preglacial fluvial origin, or was possibly a combination of both." (Davies and Holysh, 2004, pg 27-5) Above the bedrock are the "Lower Sediments" (as styled by the Geological Survey of Canada), consisting of diamict and fine-grained glaciolacustrine sediments at its base, and an upper sandy aquifer layer. (Davies and Holysh, 2004, pg 27-5). Overlaying this is a thick sequence of "Newmarket Till", a sandy loam sedimentary layer common in the area.