330 JESSE E. HYDE 
in Coal-measures rocks in such condition that they must have been 
coal at the time of their erosion—this too with no evidence of deep 
erosion of previously formed Coal-measures at any time during the 
accumulation of the whole—shows conclusively that the organic 
beds, within very short periods after their accumulation, had 
suffered most of the changes which resulted in the formation of 
coal from them. 
