Helsby Sandstone Formation
New Red Sandstone Supergroup > Sherwood Sandstone Group > Helsby Sandstone Formation
Age: Triassic > (Anisian Age) 247 – 241 Ma
The Helsby Sandstone (better known in the West Midlands by its former name Bromsgrove Sandstone) is a sedimentary rock mainly deposited by water (fluvatile deposition). Closeup it is formed of often rounded quartz grains coated in iron oxide – the red colour. The rounded grains suggests grains that have been transported by wind – aeolian transport. So we have a rock formed by water deposition of desert wind and water transported sand grains. Helsby (the type locality of this sandstone) is a village in Cheshire.
Beds of soft red fine to medium-grained sandstone deposited by rivers crossing the Triassic desert. From the direction of cross-bedding the overall flow direction is west to east.
Helsby Sandstone in the B4204 road cutting on the north side of the village, opposite Scar Cottage. This exposure includes beds of conglomerate and mudstones. There are numerous erosion surfaces, formed by river channels cutting into earlier deposits.
Reconstruction of possible environment at the time the Helsby Sandstone was deposited. The view is to the north. The river system had an overall south to north flow direction, with tributaries flowing from west and east.
Reconstruction south view.
The rivers were seasonal, probably charged with water during times of monsoons or storms in the desert.
Below a selection of the creatures of the time, including one of which remains gave been found in Helsby Sandstone.
