vol. xx. (3) THE SILURIAN ROCKS OF MAY HILL 
213 
From a consideration of the above table it is obvious that 
the Silurian deposits thin out towards the south and east, and 
that the upheaval and erosion which took place in late Silurian 
times is most marked to the south in the Mendip area, where all 
the Silurian beds down to the Llandovery are wanting, while 
in the Tortworth area the Wenlock and possibly a few inches 
of Ludlow beds are seen between the Old Red Sandstone and 
the Llandovery rocks. 
In the districts to the north of the Severn there is no evidence 
of denudation of the Silurian beds, but as one goes northwards 
each member of the Silurian series above the Llandovery beds 
thickens, which points to the gradual deepening of the Silurian 
sea in that direction. 
In Ludlow times the shore line was close to Tortworth, in 
Downton times it was a little to the south of Blaisdon in the 
May Hill area. 
The land to the south of the Bristol Channel stretched in 
late Silurian times towards the south-west, and in Old Red 
Sandstone times the Silurian deposits of May Hill and the 
Malverns were covered conformably and those farther to the 
south unconformably by the Old Red Sandstone, owing to a 
depression of those areas. Farther to the south-west the old 
land surface may well have continued to be above sea level in 
Old Red Sandstone times, and have constituted the barrier 
between the Devonian deposits and the Somerset, Gloucester- 
shire and South Wales Old Red Sandstone. 
V. General Remarks on the Fossils. 
The Llandovery beds all belong to the Upper Llandovery 
horizon, for though fossils are not at all common in the Huntley 
Hill beds, Ccelospira hemispherica is abundant where it has 
been found. 
The Yartleton beds include the same fossil and also Stropheo- 
donta compressa and Palceocyclus prceacutus, and the general 
assemblage is a typical LIpper Llandovery one. 
The Stricklandinia lirata from a calcareous band in the stream 
running down to Hay Farm is in a very unusual state of 
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