108 
hood of Tortworth, with corresponding outcrops in the Mendips, 
it seems strange that no vestige of Silurian rock has hitherto been 
met with there. In the neighbourhood of Charfield Station, the 
distance from the Lower Limestone Shales across the outcrop of 
Old Red Sandstone to the nearest point of the Silurian is only 
770 yards, and at Tortworth Court the entire outcrop of Old Red 
Sandstone is comprised within a distance of 550 yards; but 
although at Downhead, a mile and a half of stratification intervenes 
between the outcrop of the Mountain Limestone Shales on the 
north side of the anticlinal and the corresponding outcrop on the 
south, and steep inclinations prevail throughout the entire area, 
no trace of Silurian has yet been discovered. The inference to 
be drawn from it is that the thickness of the Old Red Sandstone 
on the Mendips must be immensely greater than at Tortworth, 
but it also suggests the possibility of detecting traces of the 
Silurian somewhere in the Mendip area. 
On looking at the extensive exposure of Trap at Downhead 
which far exceeds that of all the rest of Mendip put together, 
it is not surprising that the Carboniferous strata adjoining present 
evidences of greater disturbance than at any other part of the 
Somersetshire Coalfield. 
OLD DOWN. 
In an earlier number of the Proceedings of this Society, the 
Rey. H. H. Winwood called attention to a very remarkable 
section in the Rhetic formation, which occurs in a cutting on the 
Somerset and Dorset railway, near Lynch House. 
A little farther to the west, on the turnpike road, leading from 
Old Down Inn to Gurney Slade, there is another exposure of the 
same formation which does not appear to have been noticed 
hitherto, although it has now been open for some years. On leaving 
Old Down, the turnpike passes for some distance along the top 
of the Rhetic without its being seen, but on nearing the Somerset 
