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HARDWICKE'S SCIENCE-GOSSIP. 



GEOLOGY. 



Correlation of the Drift-deposits. — Mr. 

 D. Mackintosh, F.G.S., has just contributed a paper 

 on this subject to the Geological Society. The 

 object of the author was to present the subject in a 

 concise form so as to stimulate to further research. 

 His scheme of correlation was founded on the 

 horizontal continuity of the deposits and their included 

 erratics. He gave an account of his discovery of the 

 continuous extension of the upper Boulder-clay of 

 Cheshire, above a great thickness of sand and gravel, 

 as far as Berrington, south of Shrewsbury, and its 

 appearance at intervals along the Severn valley to 

 below Worcester, where it was probably represented 

 by a bed with Malvern-hill boulders above shelly 

 sand and gravel. He traced the great boulder- 

 bearing clay and gravel around Wolverhampton 

 eastward through central England, to where it 

 graduated into the chalky clay of Lincolnshire ; and 

 laid great stress on the commingling, at Wolver- 

 hampton, in this deposit, of erratics (chiefly granite 

 and felstone) from the north with erratics (chiefly 

 chalk-flints and gryphites) from the east. He described 

 the clay and sand around Gainsborough, Retford, &c. 

 He correlated the "carrion," or lower Boulder-clay 

 of the Vale of York (containing Carboniferous, 

 Jurassic, and granitic erratics), with the lower 

 yellowish-brown clay of the Aire and Wharfe valleys 

 and the plain of Craven. He likewise correlated 

 patches of upper clay in the latter areas with the 

 upper Boulder-clay of the Lancashire plain, but was 

 not certain that they were of Hessle age. The 

 solution of the main question depended chiefly on 

 the relative age of the Wolverhampton and Stafford 

 clay-and-gravel, which he was disposed to regard as 

 the equivalent of the lower brown Boulder-clay of 

 the north-west and likewise of the chalky clay of 

 Lincolnshire. 



The Portland Rocks of England. — At a recent 

 meeting of the Geological Society, a paper on this 

 subject was read by the Rev. J. F. Blake, M.A., F.G.S. 

 The author gave a general account of the relation 

 of the several Portland rocks in the areas of their 

 development to each other, and hence deduced the 

 history of the Portland " episode." The name is 

 used on the continent in a wider sense than in 

 England, and this use was shown to be unjustifiable. 

 After giving an account of his observations on the 

 rocks at Portland itself, and dividing the limestones 

 into the building-stone and flinty series, the author 

 showed that the so-called "Upper Portlandian" of 

 Boulogne corresponds to the latter, and the upper 

 part of the "Middle Portlandian" to the Portland 

 sand. He then endeavoured to prove by the propor- 

 tionate thickness, the indications of change in the 

 lithology, and the distribution of some of the fossils, 



that the rest of the so-called " Middle " and the 

 "Lower Portlandian" are represented by integral 

 portions of the Upper Kimmeridge, which are thus 

 the "normal" form corresponding to what the 

 author calls the " Boulognian episode." The series 

 in the vale of Wardour has been made out pretty 

 completely. The Purbeck is separated by a band of 

 clay from the Portland and is not amalgamated with 

 it. The building-stones, and flinty series are here seen 

 again ; and a fine freestone occurs at the base of the 

 latter. The representatives of the Portland sand were 

 considered to be older than those of other districts. 

 The relations of the Purbeck to the Portland rocks at 

 Swindon were very carefully traced ; and it is shown 

 that, while the upper beds of the latter put on here 

 some peculiar characters, the former lie on their worn 

 edges. The upper beds of the Portland, which have 

 been referred to the sand, correspond to the freestone 

 and the base of the flinty series of the Vale of War- 

 dour ; hence the Purbecks of Swindon may be coeval 

 with the upper beds of the Portland to the south. 

 At the base of the great quarry and elsewhere in 

 the neighbourhood are the " Trigonia-beds," beneath 

 which is clay, hitherto mistaken for the Kimmeridge 

 Clay ; and beneath this are the true Portland sands, 

 with an abundant fauna new to England. The lime- 

 stones of Oxfordshire and Bucks were considered to 

 represent the "Trigonia-beds" only; and, as the 

 Purbecks here lie for the most part conformably, it 

 was suggested that they wore formed in a lake at an 

 earlier period than those at Swindon, which are of a 

 more fluviatile character. Hence the Portland episode 

 considered as marine, was at an end in the north 

 before it was half completed in the south. 



Cave-hunting.— Messrs. James and W. E. Back- 

 house, by whom the interesting " Teesdale Cave" 

 was discovered in 1878, obtained during the last season 

 the bones of twenty-two vertebrate animals, including 

 a species of the cat tribe. Mr. W. Davies of the British 

 Museum, thinks it to be the lynx. We believe that 

 lynx bones have been found in a Derbyshire cave. 



The Volcanic Rocks of Dartmoor. — At a 

 recent meeting of the Geological Society, a paper 

 was read on this subject by Mr. Frank Rutley, F.G.S. 

 Among the ashy beds of this district are certain 

 amygdaloidal schistose rocks, which the author is of 

 opinion are really lava-flows, which have probably 

 been crushed or infiltrated, and have so assumed a 

 foliated structure owing to pressure from superin- 

 cumbent beds acting on rocks thus constituted. They 

 are much altered, but were probably once basalts. 

 The author considered it very probable that these 

 schistose beds and Brent Tor, considered to be of 

 Carboniferous age, are identical with beds near Tavis- 

 tock and in the Saltash district, which are of Upper 

 Devonian age. In the concluding part of the paper 

 the author described the beds of alternating ashes and 



