90 



HARDWICKE'S SC IENC E-GOSSIP. 



from correspondents of Science-Gosslt that plants 

 three or four years old, with hardened wood and 

 bark, have not been killed, and that the cultivation 

 of a tree in which so much interest has been taken 

 may be persevered in. It may, however, I think, 

 be taken for granted that for the first year or two 

 precaution should be taken to protect from the 

 frost.— T. B. JF., Brighton. 



GEOLOGY. 



The Kimmeridge Clay of England. — This was 

 the subject of a paper by the Rev. J. E. Blake, M.A., 

 F.G.S., recently read at the Geological Society. 

 The author described, in considerable detail, the 

 development of the Kimmeridge clay in various 

 parts of England, dwelling especially upon the palae- 

 ontological phenomena presented by it in the different 

 localities. He arrived at the conclusion that the 

 Kimmeridge clay in England is divisible only into 

 two sections, Upper and Lower ; but when it is pre- 

 ceded by the Coral Rag, it possesses a basal series 

 of no great thickness, which may be designated the 

 Kimmeridge Passage-beds. He compared his 

 Upper Kimmeridge with the lower part of the 

 " Virgulien " of foreign authors. It consists of 

 paper shales, paper slabs, bituminous shales, and 

 cement-stones, with interstratified clays, and may 

 attain a thickness of at least 650 feet. Its fauna is 

 characterized by paucity of species and great abun- 

 dance of individuals. It is thickest in Dorsetshire 

 and Lincolnshire, but thin or absent in the inland 

 counties. The author stated that no fauna com- 

 parable with that of the Middle Kimmeridge, or 

 " Pterocerien," has beeu discovered in England, 

 though some of its less characteristic fossils occur 

 associated with Lower-Kimmeridge forms. The 

 Lower Kimmeridge is a mass of blue or sandy clay, 

 with numerous calcareous " doggers," largely de- 

 veloped in Lincolnshire, the whole representing 

 the " Astartien" of foreign geologists. Its thick- 

 ness is estimated at from 300 to 500 feet, in Ring- 

 stead Bay, and about 400 feet in Lincolnshire. The 

 fossils of the Coral Rag extend up into the Kim- 

 meridge passage-beds, which are typically'developed 

 at Weymouth, where they are about 20 feet thick. 



The Cambridge Gatjlt and Geeensand. — This 

 was the subject of a paper read at the same meeting 

 of the Geological Society, by A. J. Jukes-Browne, 

 E.G.S. This paper has for its object to determine 

 the true position of the Cambridge nodule-bed in 

 the Cretaceous series, and to investigate the nature 

 and origin of its peculiar fauna. The first part of 

 the paper deals with the stratigraphical relations of 

 the beds ; and the author calls attention to the fact 

 that in the numerous artificial sections near Cam- 

 bridge only two formations are really visible, viz., 



the chalk marl with a pebble-bed of phosphatic 

 nodules at the base, and the stiff dark clay of the 

 Gault, upon which these rest. The so-called green- 

 sand or nodule-bed passes up into the chalk marl, 

 but rests uuconformably on the gault below, which 

 presents, in fact, a surface of erosion ; and there is, 

 therefore, a break of indefinite length between the 

 Cambridge Gault and Greensand. The nodule-bed 

 continues to present much the same characters and 

 fossils through Bedfordshire as far as Sharpenhoe, a 

 village about three miles east of Harlington, on the 

 Midland Railway. Here is situated the most 

 westerly coprolite pit or working in the Cambridge 

 bed; and beyond this the gault passes into chalk 

 marl without any such seam intervening. It is not 

 until we enter Buckinghamshire and reach Buck- 

 land, near Tring, that anything like true upper 

 greensand appears, and separates the chalk marl 

 from the gault. From this point westward the 

 formation increases in thickness and importance, 

 but its characters and fossils are quite different 

 from those of the Cambridge greensand. Although, 

 in Bucks, no coprolites are found between the gault 

 aud greensand, yet they occur in the gault itself; 

 and one bed may be traced towards the N.E., and 

 is found to commence where the Cambridge nodule- 

 bed ends ; thereby raising the presumption that it 

 becomes confluent with that bed, and has furnished 

 many of the well-known fossils and nodules it con- 

 tains. A consideration of these facts warrants the 

 following general conclusions : — 1. That the Cam- 

 bridge greensand or nodule-bed has no connection 

 with the upper greensand, its actual position being 

 at the base of the true chalk marl. 2. That the 

 same bed rests unconformably on the clay below, 

 and that its coprolites and fossils have been derived 

 from the gault. 3. That in consequence of this 

 erosion a great gap now exists in Cambridgeshire 

 between the lower gault and the chalk marl, the 

 whole of the upper gault and upper greensand 

 being absent. The palaeontological evidence leads 

 to exactly the same conclusions. The fauna is 

 divisible into two groups, and the fossils belonging to 

 the one are preserved in dark phosphate, and being 

 generally waterworn, are clearly derived forms, while 

 the others are of lighter colour, and belong to the 

 deposit. The former group is chiefly composed of 

 gault species, 70 per cent, of which belong to the 

 upper stage of that formation ; while the fossils 

 proper to the 'deposit are also found in the chalk 

 marl above. The author therefore feels justified in 

 concluding that, stratigraphically, the bed is chalk 

 marl, while, palacontologically considered, its fauna 

 is mainly derived from the upper gault. 



Basalt.— In No. 123 you notice a paper by Mr. 

 R. Mallet, C.E., F.R.S., on this rock, in which he 

 shows " that all the salient phenomena of prismatic 

 basalt can be accounted for by cooling, and that the 



