Sand Overlain Research Articles

Biostratigraphy and paleoecology of Pleistocene deposits (Riddell Member, Floral Formation, Late Rancholabrean), Saskatoon, Canada

The Pleistocene Floral Formation has been described from across central and southern Saskatchewan. In the Saskatoon area it comprises four distinct lithological units: a basal sand overlain by till and an upper sand overlain by till. The upper sand, here named the Riddell Member, contains the rich vertebrate composite Riddell fauna. The fossils are sufficiently distinctive to date the Riddell Member as Late Rancholabrean. This age is considerably younger than the age of the Wascana Creek ash and indicates that various deposits assigned to the Floral Formation are not correlative.Paleoecological analysis indicates that five ecological communities are represented in the composite Riddell fauna; the largest and most extensive habitat is the dry upland prairie. The sympatry of the represented taxa is unusual for central Saskatchewan and suggests that a temperate, equable climate prevailed. Paleoenvironmental reconstruction implies that the Riddell fauna is not synchronous with the Echo Lake fauna, but may be synchronous with the "Sangamon fauna" from Medicine Hat, Alberta.

A recent, possibly catastrophic burial in a marine molluscan community

Summary A shallow water benthic sample from off the east coast of the Coromandel Peninsula contained compact shelly sand overlain by mud. The fauna, confined to the sand layer, consisted of infaunal bivalves dominated by Tawera spissa (Deshayes). The presence of dead or decaying bivalves only, indicates a heavy mortality in the community attributed to burial by the mud layer.

Pre-Selma Upper Cretaceous Stratigraphy of Western Alabama

The pre-Selma Upper Cretaceous deposits of western Alabama have long been divided into the Tuscaloosa and Eutaw formations but recent field work shows that six stratigraphic units of formational rank can be mapped: Eutaw formation McShan formation Tuscaloosa group Gordo formation Coker formation Eoline formation Cottondale formation The contacts separating these units are unconformable with the possible exception of that between the Cottondale and the Eoline formations. The Cottondale formation consists of cross-bedded fine to coarse, somewhat gravelly sand and carbonaceous clay that locally contains a rich flora. In origin it may be entirely continental or in part marine. The Eoline formation is a marine formation which commonly consists of cross-bedded glauconitic sand overlain by laminated somewhat carbonaceous clay. The Coker formation consists of highly cross-bedded and lenticular beds of sand and ferruginous clay, and is probably non-marine. The Gordo formation also consists of cross-bedded sand and mottled ferruginous and carbonaceous clay, but is the only formation of the Tuscaloosa group that contains large amounts of gravel. Throughout the area thus far studied in detail most of the gravel is chert. The formation is probably non-marine. The McShan formation is marine and has generally been included with the Eutaw formation, but an important and widespread unconformity separates it from the restricted Eutaw. It consists of finely glauconitic very fine sand and laminated sandy clay. The Eutaw formation, in contrast to the McShan, contains much coarser glauconite and much more compact gray shale. The top member of the Eutaw is the oldest Cretaceous bed that contains abundant fossil shells on the outcrop. All six formations have been recognized in wells as far downdip as Lauderdale and Neshoba counties, Mississippi.