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are met with, and on the left hand a large trough of reddish 
coloured limestones and clays are seen on the top of the up- 
turned Paleozoic; these on examination prove to be fine 
erained beds and clays of the Triassic Conglomerate, assuming 
their red colour, due probably to the infiltration of iron from 
the Red Marls which overlaid them. Fine exposures of solid 
limestones are passed through with a more or less varying dip, 
having near their base some Oolitic beds about 50 feet thick, 
succeeded by shaly limestone beds with the usual Lower Lime- 
stone characteristic fossils. 
The black clays and shales are just discernible beneath 
bridge (No. 16,) and continues as far as the first telegraph post 
on the right hand side of the line, where the so-called “ Bryozra 
bed” crops up corresponding with the position of the same bed 
in the Avon gorge Section. The colour of the bed is reddish 
brown and grey, with rusty looking streaks, which when looked 
at with a high power, are seen to be beautiful Polyzoan forms ; 
in fact a microscopic section shows that this bed is made up of 
Polyzoa, Foraminifera, encrinital stems, and here and there an 
organism which Mr Wethered considers to be a monticulipora. 
The succeeding sandstones and clays are not well seen 
owing to the growth of vegetation on the banks, but enough 
has been exposed to indicate where the Lower Limestone shales 
die out and are succeeded by the Old Red Sandstones and 
Conglomerates. Coarse beds of this formation crop up just 
before the last tunnel, and on coming out at the Thornbury end, 
are seen rising up from beneath the Dolomitic Conglomerate, 
and only distinguished from the newer beds by the direction of 
the bedding. The Old Red Conglomerate shows small faults 
and slickensides, and at one place on the right hand side, the 
beds are quite perpendicular, whilst the Dolomitic Conglomerate 
rests horizontally but unconformably on the top. Both the 
Conglomerates are of the same red colour, the older containing 
large pebbles of white quartz, the more recent also having these 
quartz pebbles at its base, with here and there an Old Red 
Sandstone pebble, and higher up those of Carboniferous Lime- 
stone, in some cases quite angular, and of considerable size. 
