GEOLOGY OF SCMERSET. 133 
New red sand stone comes next in order, being 
the overlaying rocks of the coal measures. In 
Somerset this is an extensive and varied series of 
deposits ; it is derived from the disturbed strata of 
older formations, and known as grauwacke conglo- 
merate, magnesian conglomerate, red marl and 
red sand. Several varieties of these rocks are 
strong features of the grauwacke district, and 
the magnesian conglomerate, or dolomite, forms an 
important part of the carboniferous and coal dis- 
tricets. These rocks are made up of angular fragments 
of contiguous strata; or of such as have been 
brought by the action of water from a moderate 
distance, and are slightly abraded; or of thoroughly 
abraded fragments, as those are which compose the 
shingle bank, the boundary of the channel from Stol- 
ford to Sherton. In the western district, many of 
these rocks contain pebbles of limestone in great 
abundance, and are called popple rocks; they are 
extensively worked for lime in many places. 
In the neighbourhood of Milverton and Wivel- 
iscombe, the limestone in the conglomerate beds is 
much worn by abrasion, and they contain such 
fossils, and have such other characters, as may lead 
geologists to look to the spaces between Mendip- 
hills and the Holmes, as the localities from which 
these water-worn pieces of carboniferous lime-stone 
rock were derived. 
Mount Radford, near Bridgwater, is composed 
of drifted sand, and small and large rounded and 
