Red marl thin section slide taken from Lower Triassic strata belonging to the Mercia Mudstone Group, formerly known as the Keuper Marls. Marl describes rock which is a calcium carbonate rich i.e. 35% – 65% CaCO3 with the remainder being clay with varying amounts of silt. The red marl owes its colour to oxidised iron compounds present in the sediment. This material was deposited in Sahara-like desert conditions when the British Isles was thought to have been about 15 degrees north of the Equator. We collected this particular material around Westbury upon Severn in Gloucestershire, UK. The slides are 30 microns thick and measure 46 x 27 mm in size and have a cover slip of the section along with a protective cardboard sleeve.
