264 



LYTH HILL.— SHARPSTONE HILL. — HAUGHMOND HILL. 



never repaid the speculators. Similar adventures have been made amid the disturbed strata below 

 Lyd's Hole and with no greater success. 



The central mass of Pontesford Hill is composed of trap rocks, which rise in a double bossed 

 outline to the height of 950 feet above the sea. The summit consists chiefly of a fine-grained cry- 

 stalline dark-coloured greenstone, with occasionally small grains of steatite and some quartz finely 

 asseminated. Near the south-west end of the hill and above the village of Habberley the rock 

 passes into a beautiful amygdaloid, having a base of dark purple compact felspar, and kernels of 

 calcareous spar and green earth. There are other varieties of this amygdaloid, which in the opposite 

 side of the hill pass into a grey porphyry. Some of the amygdaloids contain concretions of quartz 

 as large as hens' eggs. A common variety of the trap is a deep purple compact felspar, with much 

 lime both disseminated and in strings. 



The dykes of trap laid bare in the contiguous chasm of Lyd's Hole, and which have produced the 

 alterations in the sedimentary rocks above described, are as follows : 



1. Small concretionary dark purple felspar with veins of carbonate of lime, occasionally coated by films of steatite or 

 serpentine : the concretionary structure being sometimes lost it passes into a simple felspar rock. 



2. Dark purple and white amygdaloid, the base charged with iron and a little disseminated lime. 



3. Pale green compact felspar rock, here and there inclosing small portions of schist. 



Trap of Lyth Hill, Sharpstone Hill, and Haughmond Hill, near Shrewsbury. 



Other parallel lines of trap, having a true south-westerly and north-easterly direction, 

 in conformity with the strike of the elevated strata of the slates and sandstone of the 

 Cambrian System, are observable at various points from the southern end of Lyth Hill 

 to Bayston or Sharpstone Hill near Shrewsbury. 



At Stapleton Alms House is a dyke of coarse-grained crystalline greenstone, which throws off 

 vertical beds of purplish grit and sandstone ; and a similar rock is quarried on the south-western 

 face of Lyth Hill, near the spot where it rises in a conical form through the same sandstones and 

 grits, which at the point of contact with the trap are veined and contain druses coated with anthra- 

 cite and calcareous spar. Some of this anthracite is in a viscid state and runs out from the cavities 

 in the state of mineral pitch \ other portions are completely charred, resembling cinders. We shall 

 presently point out a much more remarkable instance of this phenomenon in similar rock at Haugh- 

 mond Hill. Traces of copper ore have also been detected. 



In Bayston or Sharpstone Hill the trap forms small dykes, irregularly parallel to the strike of the 

 vertical beds of sandstone, schist, and conglomerate. It is there a greenstone both coarse and fine- 

 grained, being for the most part in a decomposing state ; with it is a conglomerate made up of 

 pebbles of quartz and indurated clay, with a base apparently similar to that of the trap. 



Beyond these low hills, about two and a half miles south of Shrewsbury, is a depression in the pro- 

 longation of the Cambrian strata (the valley of the Severn), which is filled up with patches of the 

 coal measures at Sutton and Uffington overlaid and surrounded by much of the Lower New Red 

 Sandstone. (See p. 81 et seq., with view.) 



Haughmond Hill. — This hill, rising from the low country of red sandstone and car- 

 boniferous strata as represented in the left hand of the view p. 81, is composed, like the 



