78 



DATE OF ERUPTIONS IN THE ABBERLEY AND CLENT HILLS. 



rocks which in the map and sectional illustrations appear in immediate relation to strata 

 already described (the New Red System). I am, however, acquainted with one example 

 only in this region, where trap can be seen to have been intruded into the New Red Sand- 

 stone; and this intrusion having taken place on a line of ancient volcanic eruption, the 

 origin of which cannot be understood without a previous acquaintance with the history of 

 the Silurian System, the account of this new red trap dyke is necessarily deferred to a 

 subsequent chapter. In like manner, I postpone the consideration of those peculiar trap 

 rocks, which rising to the surface in the Abberley and Clent Hills and adjacent tracts, 

 frequently separate the New Red Sandstone from the coal-measures, for their relation 

 cannot be comprehended until the carboniferous strata with which they are associated 

 have been described. This class of trap rocks, though evidently of intrusive cha- 

 racters, yet carries with it unequivocal proofs of the period of its emission, and is, 

 therefore, a marked exception to the eruptive rocks previously alluded to, the age 

 of which is not bounded by clear geological limits ; for, as already briefly hinted at, 

 the syenites, porphyries, or other felspathic rocks of which these hills are composed, 

 were manifestly erupted before the accumulation of the greater portion of the New Red 

 Sandstone, since fragments of them occur abundantly in conglomerates near the lower 

 part of that system. On the other hand, as some of the adjacent carboniferous strata 

 are shattered and highly dislocated, ample proof is afforded, that these trap rocks 

 must have been thrown up, either towards the close of the carboniferous sera or during 

 the earliest period of the New Red System ; and thus we have a right to affirm that 

 the epoch of their eruption is fixed 1 . 



After this digression explanatory of the rocks of igneous origin, we may again pro- 

 ceed to consider the stratified deposits in their regular sequence, commencing with the 

 upper surface of the carboniferous series, at which we had already arrived in descending 

 order ; simply premising, that after the explanation here given, the description of trap 

 rocks, wherever they occur, will, in each succeeding chapter, follow the account of the 

 sedimentary deposits with which they are associated. 



1 The reader will better understand the object of this chapter after consulting the small coloured sections II. 

 and III. which are placed upon the margin of the map. 



The opposite sketch is taken from the upper part of Hagley Park, the seat of Lord Lyttelton, placed on 

 the north-western slope of the Clent Hills, one of the trappean ridges alluded to in the text ; the Malvern 

 Hills, which are also of the same class, appearing in the distance. The Abberley Hills, or northern prolonga- 

 tion of the Malverns, are seen from the same spot, but can be included only in a panoramic drawing. The low 

 country or plain of Worcester is occupied by the New Red Sandstone described in the previous chapters. 

 I am indebted to Mrs. T. Phillips for this beautiful drawing. 



