282 Intelligence and Miscellaneous Articles. 



Practically the several formations consist of old sea-bottoms, 

 formed out of material derived from the degradation of old land- 

 surfaces. The exceptions are trifling, such as the under-lay ers 

 of coal-seams, and dirt-beds like those at Portland. The trans- 

 formation of an old land-surface into a sea-bottom will probably 

 obliterate every trace of glaciation ; even the stones would be 

 deprived of their ice-markings ; the preservation of Boulder-clay, as 

 such, would be exceptional. The absence of large erratic blocks in 

 the stratified beds may indicate a period of extreme glaciation, or 

 one absolutely free from ice. The more complete the glaciation the 

 less probability of the ice-sheet containing any blocks, since the 

 rocks would be covered up. Because there are no large boulders in 

 the strata of Greenland or Spitzbergen, Nordenskjold maintains 

 that there were no glacial conditions there down to the termination 

 of the Miocene period. The author maintained that glaciation is 

 the normal condition of polar regions, and if these at any time were 

 free from ice, it could only arise from exceptional circumstances, 

 such as a peculiar distribution of land and water. It was extremely 

 improbable that such a state of things could have prevailed during the 

 whole of the long period from the Silurian to the close of the 

 Tertiary. 



A million years hence it would be difficult to find any trace of 

 what we now call the glacial epoch ; though if the stratified rocks 

 of the Earth's crust consisted of old land- surfaces, instead of old 

 sea-bottoms, traces of many glacial periods might be detected. The 

 present land-surface will be entirely destroyed in order to form the 

 future sea-bottom. It is only those objects which lie in existing 

 sea-bottoms which will remain as monuments of the Post-tertiary 

 glacial epoch. Is it, then, probable that the geologist of the future 

 will find in the rocks formed out of the non-existing sea-bottom 

 more evidence of a glacial epoch during Post-tertiary times than we 

 now do of one, saj% during the Miocene, Eocene, or Permian period ? 

 Palaeontology can afford but little reliable information as to the 

 existence of former glacial periods. 



2. " On Eemains of Eocene and Mesozoic Chelonia, and on a 

 Tooth of (?) Omithopsis:' By E. Lydekker, Esq., B.A., F.G.S. 



3. " On the Dentition of Lepidotus maoaimus, Wagn., as indicated 

 by specimens from the Kimeridge Clay of Shotover Hill, near 

 Oxford." By R. Etheridge, Esq., F.R.S., F.G.S., and H. WiUett, 

 Esq., F.G.S. 



XXXIII. Intelligence and Miscellaneous Articles. 



ON IRRECIPEOCAL CONDUCTION. BY DR. C. FEOMME, 

 PROFESSOR OF PHYSICS IN THE UNIVEESITY OF GIESSEN*. 



IN the August number of the Philosophical Magazine, which 

 has only just now come to my notice, Messrs. Haldane Gee 

 and Holden have published experiments relating to the resistance 

 of a voltameter with platinum electrodes filled with strong sul- 

 * Communicated by the Author. 



