July 29, 1 875 J 



NATURE 



263 



SOCIETIES AND ACADEMIES 



London 



Geological Society, June 23.*— Mr. John Evan?, V.P.R.S., 

 president, in the chair. — On the Granitoid and associated Meta- 

 morphic Rocks of the Lake-dis-trict, by J. Clifton Ward. 



Part I. On the Liquid CavitiiS in the Quartz- bearing Rocks of the 

 Lake-disttict. — The object of this paper was to examine into the 

 evidence afforded by the liquid cavities of the granitoid rocks of 

 the Lake-district, with reference to the pressure under which these 

 rocks may have consolidated. In the first division of the subject the 

 geological relations of the three granitic centres of the district 

 were considered, and it was shown that these several granitic 

 masses probably solidified at depths varying from 14,000 feet to 

 30,000 feet. The most probable maxnnum depth for the Skidda'v 

 granite was stated as 30,000 feet ; the maximum for the Eskdale 

 granite 22,000 leet ; and for the Shap granite 14,000 feet. These 

 maximum depths were arrived at by estimating the greatest 

 thickness of strata that were ever, at one time, accumulated 

 above the horizon of the top of the Skiddaw slates. The mode 

 of microscopic examination, together with a description of the 

 precautions taken in measuring the relative sizes of the cavities 

 and their contained vacuities, formed the second division of the 

 paper. It was stated that all the measurements used in the 

 calculations were made from cases in which the vacuity mixed 

 freely in the liquid of the cavity, and an approximately ptrftct 

 case for measurement was defined to be one in which the outline 

 of the liquid cavity was sharply defined all round in one fo.us, 

 and in which the vacuity moved freely to every part of the cavity 

 without going out cf focus. Then followed the general results of 

 the examination. Restricting the measurements to such cases as 

 those above mentioned, the results were found to be generally 

 consistent with one another, and with those previously obtained 

 by Mr. Sorby in his examination of other granitic districts. 

 From the fact that the calculated pressure in feet of rock was in 

 all cases greatly in excess of the pressure which could have 

 resulted from the thickness of overlying rocks, it was inferred as 

 probable that these granitic masses were not directly connected 

 with volcanic action, by which the pressure might have been 

 relieved, but that the surplus pressure was spent in the work of 

 elevation and contortion of the overlying rocks. Microscopic, 

 combined with field evidence, was thought to indicate that the 

 Shap granite, though mainly formed at a depth similar to that 

 at which the Eskdale granite consolidated, was yet itself finally 

 consolidated at a much less depth, the mass having eaten its way 

 upwards at a certain point, and perhaps representing an unsuc- 

 cessful effort towards the formation of a volcanic centre. The 

 examination showed that the mean of the pressures under which 

 the Lake-district granites probably consolidated was nearly the 

 same as the mean which Mr. Sorby arrived at for those of Corn- 

 wall. In conclusion the author stated that he wished these 

 results to be considered as preliminary only, since the complete 

 investigation would necessarily occupy far more time than was 

 at his disposal ; at the same time he ventured to hope xhnigeneral 

 accuracy was insured, while pointing to the many little-known 

 causes which might affect the conclusions. 



Part II. On the Eskdale and Shap Granites, with thiir associated 

 Metamorphic Rocks. — The author brought forward evidence in 

 this paper to prove the possibility of the formation of granite by 

 the extreme metamorphism of volcanic rocks. The passage is 

 shown in the field, and may be observed in a complete series of 

 hand specimens. Frequently, indeed, the actual junction is well 

 marked, but in other cases the transition is gradual ; and there 

 occur at some little distance from the main mass, inlying patches 

 of what may be called bastard granite. The microscopic exami- 

 nation proves the passage from a distinctly fragmentary (ash) to 

 a distinctly crystalline rock, and to granite itself. Also the 

 chemical composition of the altered rocks agrees very closely 

 with that of the granite. Both Eskdale and Shap granite were 

 believed to have been foiined mainly from the rocks of the 

 volcanic series by metamorphism at considerable depths ; but 

 the granite of Shap was thought to be in great measure intrusive 

 amongst those particular beds which are now seen around it . A 

 decided increase in the proportion of phosphoric acid was noted 

 in the volcanic recks on approaching the granite, and a decrease 

 in carbonic acid. 



On the Correlation of the Deposits in Cefn and Ponlnewjdd 

 Caves, with the Drifts of the neighbourhood, by Mr.D. Mackintosh. 

 Believing that the time has arrived for making some attempt to 



* Continued from p. 243. 



correlate cavern-deposits with glacial and interglacial drifts, the 

 author ventures to bring forward the results of a personal exami- 

 nation of the remnants of the deposits in Cefn and Pontnewydd 

 caves, compared with old accounts given by Mr. Joshua Trimmer 

 and others. He has been led to regard the following as the 

 sequence of deposits before the caves were nearly cleared out 

 (order ascending) :— i. Loam with bones and smoothly rounded 

 pebbles, nearly all local (cemented into conglomerate in Pont- 

 newydd cave). As a few foreign pebbles of felstone have beea 

 found in this bed, it could not have been deposited by the adja- 

 cent river Elwy before the great glacial submergence ; and the 

 author gives reasons for believing that it was not introduced by 

 a freshwater stream from the boulder-clay above in Post- glacial 

 times, but that it may possibly represent the middle drift of the 

 plains, and may have been washed in by the sea during the rise 

 of the land. After emergence, and during a comparatively mild 

 interglacial period, bones of animals may have been introduced 

 by rain through fissures in the roof of the cave, and these may 

 have become partly mixed up with the underlying pebbly deposit. 

 2. Stalagmite, from less than an inch to two feet in thickness, accu- 

 mulated during a continuance of favourable conditions (apparently 

 absent in Pontnewydd cave). Bones of animals were again 

 brought in by rain or by hyaenas, and were afterwards worked 

 up into the Ibllowing deposit : — 3. Clay, with bones, angular 

 and Eubangular fragments of limestone, pebbles of Denbighshire 

 sandstone, felstone, <S:c. (palaeolithic flint implements and a 

 human touth in Pontnewydd cave according to Prof. T. -M 'Kenny 

 Hughes). This clay once filled the Cefn cave nearly to the roof. 

 There are reasons for believing that it was principally introduced 

 through the mouth of the cave, that it is of the same age with 

 the neighbouring upper boulder-clay, and that it is not a fresh- 

 water redeposit of that clay. It was probably washed in during 

 a second limited submergence. 4. Loam and coarse sand charged 

 with minute iragments of sea-shells. Portions of this deposit 

 may still be found in the Cefn cave ; and it may have been intro- 

 duced through fissures in the roof by the sea as the land wag 

 finally emerging. 



Geological Notes from the State of New York, by Mr. T. G. 

 B. Lloyd, C. E. The substance of this paper comprises notes, 

 accompanied by drawings and sketches of various matters of 

 geological interest which fell under the author's observation 

 whilst residing some years ago in the State of New York. The 

 different subjects are divided under the following heads : — (l) 

 Groovings and channelings in limestone running across the bed 

 of Black River at Waterlovvn, Jefferson co. (2) Descriptions of 

 the superficial beds of boulder-clay, sand, and gravel which were 

 exposed to view in the district around the village of Theresa 

 during the construction of the Black River and Morristown rail- 

 road. (3) A description, with a general and detailed drawing to 

 scale, of a remarkable "Giant's Kettle" near Oxbow, in Jeffer- 

 son CO. (4) An account of some peculiar flower-pot-shaped 

 blocks of sandstone discovered in a quarry of Potsdam sandstone 

 at the village of Theresa. The author in conclusion refers to a 

 statement in a paper on Niagara by Mr. Belt, F.G.S., published 

 in the Quart. Journ. of Science for April 1875, in which it is stated 

 that the sections described as occurring near the Falls are typical 

 of the superficial beds that mantle the whole of the northern 

 part of the State of New York and Ohio and much of Canada, 

 lie is unable to find any description of a deposit which bears a 

 near resemblance to the boulder-clay occurring in the district 

 around the village of Theresa, in the descriptions of various 

 authors of the superficial deposits of the northern part of the 

 State of New York and Canada. He therefore ventures to 

 remark that no section can be considered as typical of the whole 

 of the north part of the State of New York which does not 

 recognise the existence of the deposit in question. 



On a Vertebrate Fossil from the Gault of Folkestone, which 

 also occurs in the Cambridge Greensand, by Prof. II. G. Seeley, 

 F.L.S. The author describes a bone having the general form 

 of an incisor tooth obtained from the Gault of Folkestone by Mr. 

 f . S. Gardner, F.G.S. The flattened cylindrical end of a speci- 

 men from the Cambridge Greensand has been figured as a caudal 

 vertebra of Pterodactylits simus. A microscopic section of the 

 expanded end of a specimen from the Cambridge Greensand 

 exhibits ordinary osseous tissue, showing that the fossil is 

 probably a dermal spine from the tail of a Dinosaur. The 

 Gault specimen is smaller than tlie examples from Cambridge. 



Royal Horticultural Society, July 7.— Scientific Com- 

 mittee.— J. D. Hooker, F.R.S., in the chair. — A paper on the 

 resting-spores of the potato disease was read by Worthington 



