What is the name given to the geological time period of 363-290 million years ago during which coal measures were formed?
Coal Seams of the South Yorkshire Coalfield not given as they vary across the coalfield. Coal Seams of the South Yorkshire Coalfield The coal seams worked in the South Yorkshire Coalfield lie mainly in the middle coal measures. These are a series of mudstones, shales, sandstones, and coal seams laid down during the Carboniferous period about 350 million years ago. The total depth of the strata is about 1.2 kilometres. The list of coal seams that follows starts at the shallowest seam and proceeds downwards with the outcrops occurring progressively further west until the deepest coal seam, the Silkstone Seam which outcropped at the western edge of
Geological period example the 'Jurassic System' of rocks was formed during the 'Jurassic Period' (between 201 and 145 million years ago). The following table includes all currently recognized periods. The table omits the time before 2500 million years ago, which is not divided into periods. See Geologic time scale#Proposed Precambrian timeline for another set of periods 4600–541 MYA. In a steady effort ongoing since 1974, the International Commission on Stratigraphy has been working to correlate the world's local stratigraphic record into one uniform planet-wide benchmarked system. American geologists have long considered the Mississippian and Pennsylvanian to be periods in their own right