2 THE GEOLOGY OF TYTHERINGTON AND GROVESEXD. 



Parm, is another valley occupied by Triassic strata. The 

 southern slope of Castle Hill is being eaten into by a large 

 quarry, worked by Mr. Hardwicke, of Tytherington. 



Beyond the station the line of rail skirts the north- 

 eastern side of the Castle Hill in a gradually deepening cut- 

 ting, in which Triassic strata are seen resting on the up- 

 turned edges of Mountain Limestone. Then curving to the 

 east, so as to run nearly along the strike of the Palaeozoic 

 strata, it enters the Tytherington tunnel ; on emerging from 

 which Triassic beds are again seen filling a denuded hollow 

 in the Mountain Limestone, Turning northwards, the cut- 

 ting then runs nearly across the edges of the Palaeozoic 

 strata, until, close to a stone bridge near Grrovesend, the 

 grass-covered slopes of the cutting indicate the incoming 

 of the softer beds, which are transitional between the Car- 

 boniferous series and the Old E.ed Sandstone. Stronger 

 and harder beds of Old Red Sandstone crop out before the 

 Grovesend Tunnel, at the northern end of which the Old 

 Red Sandstone, in places vertical, and further on showing 

 the summit of an anticlinal roll, is overlain by hard Base- 

 ment Beds of the Trias which stand in the cutting as a 

 vertical wall. These are succeeded by argillaceous lime- 

 stones and Triassic Marls, from which the line of rail 

 emerges, to run over comparative^ flat and low-lying Old 

 Red Sandstone to Thornbury. 



The hamlet of Grrovesend stands at the head of a little 

 valley of denundation draining N. by E. Lito the head 

 of this valley the Gloucester Road over Milbury Heath 

 dips. Immediately under the road is the tunnel mouth, 

 and above the road is a mural face of hard dense Old Red 

 Sandstone, partly hidden by walling. Towards Bristol the 

 road rises over Old Red Sandstone, and then dips into a 

 depression caused by the incoming of the softer Lower 



