Published online by Cambridge University Press: 01 May 2009
Metamorphism of the South Wales coals is considered to be due to depth of burial and not to a thrust. Dr. Trotter's data are used to calculate the metamorphic gradients at different places. The differences in these gradients, which are calculated in two different ways, are discussed. The South Wales gradients together with data from New Zealand are used to estimate 18,000 feet as being the total depth to which the 4 per cent anthracite was buried. Maximum depth of burial is considered due to cover unconformable to the coal measures except in the southern part of the coalfield.