472 



tain limestone ; whilst in the contiguous extension of this field, the 

 carboniferous strata overlie, unconformably, various members of the 

 grauwacke series, with one of which, the transition limestone of Wen- 

 lock Edge, they are brought into conformable apposition at Lincoln 

 Hill, on the Severn. The complicated relations of the deposits within 

 this small and disturbed district, east of the Wrekin, are referred to 

 the protrusion of basalt and green-stone, which occasionally tilt the 

 strata at high angles, and sometimes occupy the seats of faults. 



b. Coal-fields in the immediate vicinity of Shrewsbury. — Of these, 

 the most important is a curvilinear zone extending from the north- 

 eastern flank of the Brythin Hills to Wellbatch, near Shrewsbury, 

 the carboniferous strata reposing on the inclined edges of the grau- 

 wacke rocks, and dipping towards a common centre beneath the new 

 red sandstone. Detached portions of the same zone are again 

 found at Sutton and at Uffington; and they also follow the sinuous 

 outline of grauwacke on the northern flanks of the Longmynd and 

 Caer Caradoc. At Pitchford, the whole carboniferous series is re- 

 presented by a bituminous breccia of a few feet in thickness. 



Three thin beds of coal are, for the most part, observable, and 

 the deposit is distinguished by an included band of limestone, simi- 

 lar in mineral aspect to the lacustrine limestones of Central France, 

 and containing minute shells referrible to freshwater genera. The 

 vegetable remains of the associated shales are chiefly analogous to 

 the plants of other coal-basins; but those of Le Botwood are rich in 

 the new species, Neuropteris cordata, whilst the shale of Pontesbury 

 has offered a beautiful example of Pecopteris blechnoides in fructifi- 

 cation. 



After demonstrating the slight commercial value which can be 

 attached to the thin deposits of this age, the author speculates on 

 the probable importance of the outer zone or Pontesbury-field, which 

 he presumes may expand to a great thickness in its passage beneath 

 the new red sandstone of N. Shropshire and Cheshire. 



c. Coal fields in the Clee Hills. — These fields are thrown up to 

 considerable heights above the adjoining country of old red sand- 

 stone, both in the Brown Clee, and the Titterstone Clee Hills, the 

 coal being for the most part covered with basalt. 



The Brown Clee is distinguished by two tabular summits of black 

 basalt (Jewstone), the highest of which is 1806 feet above the sea. 

 The coal-bearing strata have for their base a hard sandstone occa- 

 sionally conglomeritic, the equivalent of the millstone grit. On 

 three sides of this ridge, these very thin and poor coal measures 

 repose on old red sandstone, which to the west is a coarse conglo- 

 merate ; but on the fourth or south-eastern side, there is inter- 

 posed between the old red and the lower coal grits, a thin zone of 

 limestone, which the author, therefore, refers to the age of the 

 mountain limestone. Several faults are mentioned as traversing 

 this coal tract from S.W. to N.E., one of which has been the source 

 of eruption of much basaltic matter. 



The Titterstone Clee Hill is next described; and details are pre- 

 sented of those parts only which were unnoticed in Mr. R. Wright's 



