The strata is less distinct than in natural cross stratified drift, and concave downwards patterns are common. This contrasts with the cross strata of the drift and sandstones. Grading by grain size is also evident. The patterns of cross strata in sediments such as this differ from those of the drift from which the sand was obtained. This distinct pattern is not seen in sediments formed in flume experiments, even if the same sand is used.
Laminations formed in sediments are less smooth and less distinct.
They also tend to be distorted by compaction. At the boundary of the Canadian Shield and the Paleozoic limestone cover in eastern Ontario, there is a change in the composition of the drift which mantles the region. Geologic investigations in the region provide an opportunity for comparison of rival theories of origin of the drift, by determining how well the predictions of each fit the data. The limestone bedrock in the area of the Peterborough drumlin field consists of Ordovician calcareous shales and limestones of the Black River and Trenton Groups along with basal sandstones. These overlie Precambrian granite and metasediments.