606 EBPOET— 1886. 



Passing now to Central England we come to regions whicL may be regarded as 

 almost the exclusive property of your local geologists. The HoUybush sandstone 

 on the flanks of the Malvern is, no doubt, largely composed of the finer debris of the 

 older rocks of that chain, but the Malvern hills are only an unburied fragment of 

 a vastly larger area of crystalline Archaan rock. This is just indicated some seven 

 miles farther north in the Abberley hills. It crops up at either end of the Wrekin, 

 and for a little space near Rushton, but in the later fragmental rocks of the district 

 we have abimdant proofs of its existence. The central part of the Wrekin is 

 composed of volcanic rocks, rhyolites of varied kinds, with agglomerates; these 

 were once regarded by our highest authorities as greenstones intrusive in beds of 

 Ordovician age, but Mr. S. AUport has taught us their true nature, and Dr. Calla- 

 way has proved their far greater antiquity. Similar rocks are to be found elsewhere 

 in the neighbourhood of the Wrekin, and in the district farther west. We cannot 

 affix a precise date to the volcanic outbursts of the Wrekin, but we can prove 

 that they are not newer than the quartzite which fringes the hill, as it contains 

 fragments of the perlitic and other glassy rocks of the apparently underlying series. 

 This quartzite is certainly much older than the newer part of the Cambrian, and 

 pebbles of rhyolites, resembling those of theAVrekin, occur in the indubitable Cambrian 

 beds farther west. For instance, a gi-it at Haughmond Hill is quite full of frag- 

 ments of volcanic rock, many of them scoriaceous ; another suggests the derivation of 

 some of its materials from a mica-schist, while, according to Dr. Callaway, the con- 

 glomerates and grits of the Longmynds (which form the main part of the mass) 

 are largely derived from older rocks, the former being crowded with pebbles of purple 

 rhyolite, quartz, felspar, mica, and occasional bits of mica-schist. A most interest- 

 ing conglomerate, apparently older than the quartzite, occurs at Charlton Hill. 

 This contains more or less rolled fragments of grits, qvuxrtzites, and argillites, look- 

 ing in several cases as if they had undergone, before being broken off, the usual 

 micro-mineralogical changes. It contains also fragments of rhyolite and many of 

 coarse granitoid or gneissoid rocks of Malvernian type, besides numerous grains of 

 quartz and felspar of a like character. Finer-grained gneissoid rocks and schists, 

 micaceous, hornblendic or chloritic, are present in fair amount. The last bear 

 some resemblance to the Rushton rocks, and remind me strongly of rocks which 

 occur in the Highlands and in the Alps, apparently not in the lowest part of the 

 Archaean series. Some also resemble the Anglesey schists. The quartzite itself is 

 largely made up of grains of quartz which appear to me to have been derived from 

 old granitoid rocks. Occasional grains, however, suggest, by their composite struc- 

 ture, derivation from a quartzose rock of finer texture, and, as already said, bits of 

 the Wrekin rhyolite sometimes occur. The same is true of the Lickey quartzite, 

 in regard to all three constituents, in which an occasional grain of microcline, very 

 characteristic of old granitoid rocks, has been observed. The quartz-grains in this 

 and in the former rock are occasionally very much rounded. The Lickey quartzite 

 lias lately been shown by Professor Lapworth to overlie rhyolitic rocks, and it is 

 much older than the lowest Silurian. Not improbably it is of the same age, and 

 was once connected with that of the Wrekin district. The Hartshill quartzite, 

 near Nuneaton, has a similar composition, is below Cambrian, and overlies some 

 rhyolitic rocks. Thus these insulated areas prove the existence of an old fragmental 

 series, which is largely composed of materials derived from pre-existing and much 

 more ancient Archaean rocks. It is difficult to assign a date to the unfossiliferous 

 rocks forming the rugged hills of Charnwood Forest, but, as they have been 

 affected by very ancient earth-movements, and there is nowhere any valid evidence 

 of volcanic activity in the true Cambrians, they may be assigned with most pro- 

 bability to the antecedent epoch, which seems to have been one of great disturbance. 

 Microscopic examination has shown that materials of volcanic origin enter largely 

 into the composition of these Charnwood rocks, even the most finely grained ; but 

 besides occasional fragments of slaty rock in the breccias, for which a high antiquity 

 cannot be asserted, we find some pebbles of vein-quartz and two or three beds of 

 quartzite. The grains in these appear to liave been derived from old granitoid 

 rocks, and not from the porphyritic rhyolites of the district. In one case, at the 

 Brande, they are most conspicuously rolled, and this has happened, though less 



