Sept. 7, 1SS2] 



NA TURE 



461 



erratic 1 lock < is eirmccted with the histcry if the giant glacier 

 which descended the Tees Valley, bringing, among other stones, 

 masses of the well-known Shap Fell granite. The boulders that 

 I have seen brought on shore — having been trawled up by the 

 smacks — are either of Shap granite or carboniferous limestone, 

 and of these I have examined from sixty to seventy specimens. 

 The rough ground — as far as I am aware — extends from the 

 coast of Northumberland to the mouth of the Humber. While 

 the boulder clay on the coast line contains blocks of carboni- 

 ferous limestone and Shap granite, the deposits of like date in 

 the valley of the Rye and Derwent — south of the Cleveland 

 Moor district — are composed of oolitic and liassic detritus, and 

 are very different from those on the coast, though only a few 

 miles distant from each other. 



Warwickshire. — A remarkable group of Erratic Boulders has 

 been exposed in some excavations made for building purposes in 

 Icknield Street, Birmingham, between Key Hill and Hockley 

 Hill. The section occurs on the north-west slope of the hill on 

 which it is exposed, and consists of 7 feet or S feet of glacial 

 drift (the height slightly varying at different points), which 

 immediately rests on an irregular and broken surface of the new 

 red sandstone of the district, and is composed of about I foot 

 6 inches of surface soil. The "drift " itself consists of erratic 

 blocks, intermixed with numerous round and oval stones and 

 pebbles, together with small gravel, sand and clay. In different 

 parts of the section these various materials occur in varying pro- 

 portions, a light clay gradually predominating. The erratic 

 blocks, however, so pervade the whole bed, and so thoroughly 

 constitute a component part of it, that they cannot have been 

 dragged into it, either sinjly or by twos and threes. They 

 must all have travelled together, for a certain distance, at any 

 rate, and have been brought down together to the spot at which 

 they are found. 



The felsites and the felspathic ashes are the most abundant, 

 and the Llandovery sandstones are the rarest. No block of 

 granite has been found in this group of erratics. 



Some are sub-angular ; a not inconsiderable proportion are 

 well smoothed, although they can hardly be said to be highly 

 polished ; and on a few strise may be traced. 



Prof. C. Lapworth has examined the specimens, and recog- 

 nises a large number as occurring in situ at the Berwyn Hills ; 

 others may be found in the Arenig range. 



The condition of the new red sandstone rock on which the 

 boulders rest is most remarkable. The sandstone rock is broken 

 up, and large fragments of it have been lifted up out of their 

 po-ition and thrust into the middle of the drift. At one point 

 in the section a part of the rock has been lifted up almost like 

 an arm, and still remains united with the basement ma«s while 

 the drift fills the Lshaped hollow. A large erratic block is 

 seen close to the extreme end of the uplifted arm of the base- 

 ment. 



The evidence of violence is complete. The breaking up of 

 the sandstone rock, the uplifting of parts of it en masse, and the 

 carrying away of fragments, are facts as patent as the presence 

 of the erratic blocks themselves. 



The Rev. W. Tuckwell has called the attention of the Com- 

 mittee to some very interesting boulders at Stockton, near 

 Rugby, about equi-distant from Leamington, Rugby, and 

 Coventry. One has been moved from the roadside, where it was 

 in great danger of being injured, placed upon a bed of concrete, 

 and protected by railings, 



Leicestershire. — Mr. \V. Jerome Harrison has sent the Com- 

 mittee the following note on a Leicestershire boulder which has 

 travelled northwards : — 



In the construction of the sewerage for the Clarendon Park 

 Estate, near the Victoria Park, on the east side of the town of 

 Leicester, some interesting sections of the drift were laid bare, 

 which I examined in June, 1880. Much of the drift exposed 

 was of a loamy nature, containing erratics of moderately large 

 size, and overlying, though with no well-marked line of demarca- 

 tion between, the well-known great chalky boulder clay which 

 spreads so widely in this district. 



Among the travelled rocks contained in this deposit I particu- 

 larly noticed one angular block identical in appearance with the 

 syenitic rock which forms Enderhy Knoll (four miles south-west 

 of Leicester), and Croft Hill (about two miles further in the 

 same direction). The^e South Leicestershire syenites are well- 

 characterised and somewhat abnormal rocks, and their identifica- 

 tion is easy. 



The surface of the Clarendon Park Estate is about 300 feet 



above sea-yevel, while Enierhv Knoll is about 350 feet, a:.d 

 Croft Hill 450 feet (these heights are approximations only). The 

 block w-hich I saw on the Clarendon Park Estate measured about 

 34 X 2 X 1 1 feet, and would weigh about three-quarters of a 

 ton ; it was irregular in shape and very angular. As it did not 

 interfere with the direct line of the sewer, it was not removed, 

 but was covered in. I have examined a large number of the 

 erratic blocks which stud the surface of Leicestershire, but this 

 is the only instance I know of a boulder which has been carried 

 to a distance several miles due north of its pirent rock.' 



Shropshire. — The Committee have received from Mr. Luff a 

 valuable report upon the group of erratic blocks found in the 

 neighbourhood of Clun, Shropshire. 



Prof. Lapworth has examined a series of specimens, and de- 

 scribes them as lower Llandovery grits and shales belonging to 

 the Plinlimmon group of Central Wales. The hills from which 

 they have been derived are all south of Bala, and situated almost 

 due west from their present position. 



The following are the most remarkable among a large number 

 of boulders: — The "Great Boundary Stone" marking the 

 boundary of Clun and Treverward townships. It is on Rock 

 Hill. Its dimensions are 6 feet x 6 feet x 2"5 feet. No stria- 

 tions can be detected, but it is angular and polished on one face. 

 It is a cleaved flagstone, and has travelled from a point south of 

 Machynlleth. It rests upon a bed of clay and rubble above the 

 Upper Ludlow rock. Height above the sea, 1152 feet. 



The " Black Hill Boulder;' 52° 24' 40" N. L., 2° 59' 50" W. 

 L. This boulder may be calculated to contain from 8 to 10 

 cubic feet, and is subangular. It is a pebble grit belonging to 

 the Plinlimmon group, and may have come, according to Prof. 

 Lapworth, from the neighbourhood of Rhadyr. So far as can 

 be observed, it rests upon the same limit of bed as the Great 

 Boundary Stone. Its elevation above the sea is 1327 feet, and 

 it is the highest of all the boulders of the group. 



The " 10- Feet Boulder" is a pebbly grit of the Plinlimmon 

 group. It lies on the Clun Hill, near Pen-y-wern, 52 24' 20'' 

 N. L., 3 o' 30" W. L., at an elevation of about 1160 feet above 

 the sea. It measures 10 feet x 3 feet x 3 feet, and weighs, I 

 should calculate, betw-een 6 and 7 tons. It bears every evidence 

 of having stood upright in the ground for a very long time. The 

 base is tolerably angular and well preserved, but the sides and 

 apex are much weathered. About 4 feet from the base it is 

 deeply undercut, apparently all round, exactly as we should 

 expect such a block to be where (on the ground-line) it had 

 been much exposed to the combined influence of moisture and 

 frost. 



7 the Conditions under which Ordinary Sedimentary 

 Materials may be converted into Metamorphic Rocks, l>y Prof. W . 

 I. Sollas, M.A., describes experimen's on quartz and other 

 minerals which have been subjected to a heat of 300' C. in an 

 iron tube of \ inch diameter. 



Report of the Committee for the purpose of carrying on Explora- 

 tions in Caves in Carboniferous Limestone in the South of Ireland, 

 consisting of the late Prof. A. Leith Adams, Prof. W. Boyd 

 Dawkiiis, Dr. John Evans, Mr. G. H. Kinahan, and Mr. K. 

 J. Ussher. — Within the past three months attempts have been 

 made to effect an entrance from the face of the scarp into the 

 series of caves discovered and reported on last year, in the rock 

 called the Carrigmurri-h, but after a careful survey had been 

 made and levels taken from the several branches of the caves by 

 Mr. Duffin, county surveyor, it was found that this means of 

 access is not possible. 



Eighth Report of the Committee, consisting of Prof E. Hull, 

 the Rev. H. IV. Crosskey, Capt. Douglas Gotten, Professors G. 



A. Lebour and J. Prest-vieh, and Messrs. James Glais/ier, E. 



B. Marten, IV. Molyneux, G. //. Morton, IV. Pengcliy, 

 James Plant, James Parker, I. Roberts, Fox Strangways, 

 Thos. S. Stooke, G. J. Symons, IV. Topley, Tyldeu-IVright, 

 E. Wethered, IV. Whitaker, and C. E. De Ranee, appointed 

 for the purpose of investigating the Circulation of the Under- 

 ground Waters in the Permeable Formati ns of England, and the 

 Quality and Quantity of the Water supplied to various Towns 



1 It seems to the writer to show (1) th.it a submergence followed the 

 retreat northwards of the great chalky boulder clay ; (2) that when this sub- 

 mergence amounted to about 350 or 400 feet, the bosses of syenite which 

 occur in South Leicestershire stood as little islands above the sea: (3) that 

 '" coast ice " f-rme on the margins of these islands, on which blocks of rock, 

 detached by the frost, fell : and (4) that a current running northwards carried 

 at lea<t one of these blocks down the Soar Valley, and dropped it where it 

 now lies, on the eastern brow of the Valley at Leicester. 



