NORTH DAKOTA STATE UNIVERSITY - FARGO, N D
At this roadcut east of Valley City, N.D., the students are excavating into till: compact glacial sediments that are non-layered (i.e. they demonstrate no bedding) and unsorted (i.e. they can include a mixture of particle sizes ranging from clay to boulders).
The white cobbles (erratics) at this site are of a rock type known today to outcrop in southern Manitoba. Many of these cobbles demonstrate faceted sides; this is a consequence of their having been abraded and polished by being fixed to the bottom-side of flowing ice.
The other type of glacial drift (sediment) found in North Dakota is outwash. In contrast to till, outwash demonstrates both bedding and sorting.
Because it is often rich in clay, till is generally not quarried except for use as fill.