[ 288 ] 



XLIX. On the Occurrence of Shells and Corals in a Conglo- 

 merate Bed, adherent to the face of the Trap Rocks of the 

 Malvern Hills, and full of rounded and angular fragments 

 of those rocks. By John Phillips, Esq., F.R.S., fyc. 



THE researches of Sir H. T. De la Beche during the autumn 

 of 184<1 into the nature, antiquity and organic contents 

 of the trappfean ash-beds of North Pembroke, coupled with 

 other parallel inquiries, have excited in the minds of those 

 persons who are attached to the Ordnance Geological Survey 

 a lively interest in the study of the relations between trap 

 rocks and the strata amongst which they appear. A very com- 

 mon result of this study in South Wales is a conviction of 

 the rarity of irruptive trap and the frequency of interstratified 

 (and, in ordinary language, contemporaneous) beds of plu- 

 tonic rocks and felspatho-hornblendic sediments, which are 

 not always clearly distinguished from the fused rocks. On 

 these points in the same or neighbouring districts, Professor 

 Sedgwick and Mr. Murchison deliver nearly the same judg- 

 ment. 



The great obligations which geology owes to Mr. Leonard 

 Horner and to Mr. Murchison for their descriptions of the 

 fused and sedimentary rocks in this chain, and of the grand 

 movements in the crust of the earth, of which it is a noble 

 monument, are universally admitted, but demand a glad ac- 

 knowledgement from one who, following in their steps and 

 profiting by their experience, desires to join to theirs the 

 additional information which he may be so fortunate as to 

 gather. 



After finishing the colouring of a great part of the Ord- 

 nance map of this district, I turned to examine with care and 

 interest the great problem which the Malvern hills present, 

 viz. the determination of the circumstances under which the plu- 

 tonic rocks were elevated. For this purpose the appearance 

 of the fused and sedimentary rocks in every part of the Mal- 

 vern chain and the surrounding country has been considered, 

 separately and in combination ; and the general result is, that 

 the elevation of these hills is a part of that grand series of 

 associated movements, which the Director and other mem- 

 bers of the Geological Survey have been tracing between St. 

 Bride's Bay and the Severn, between the Teivy and the Bris- 

 tol Channel. 



Viewed in this association, the geological epoch when the 

 great movement of the Malvern rocks occurred, becomes de- 

 terminable, and has in fact been determined by the eminent 

 geologists already named. No one can witness the many 



