SCIENCE-GOSSIP. 



3*3 



tended to become filled up by the deposits; but it 

 seems certain that the London area must have been 

 covered for long tracts of time by a sea resembling 

 that of some parts of the Pacific in which a rain of 

 the shells of foraminifera and other marine animals 

 gradually formed a pulverulent limestone on the 

 bottom. This sea was that of a tropical region, a 

 barrier of land towards the north shutting out the 

 colder waters and allowing warm southern currents 

 to enter it. The traces of organisms found in the 

 centre of the flint nodules which occur in layers in 

 the chalk show us the nature of the creatures 

 which existed in the sea at this time. The siliceous 

 deposit of the masses of flint seems to have gradually 

 formed around the remains of sea-urchins, sponges 

 and other marine inhabitants, the forms in some 

 cases closely resembling those now existing. 



After the long continuance of the warm tropical 

 waters, a gradual upward movement began to take 

 place ; the floor of the Cretaceous sea was raised 

 into dry land, and some of the deposits seem to 

 have been worn away by the action of denuding 

 agents at this time. 



After the time of the Chalk, in which a sea 

 resembling that now extending round the coral 

 islands in the Pacific covered the site of the 

 London basin, a shallowing of the water occurred, 

 sand was spread over the bottom, and afterwards 

 the regions became covered by the waters of an 

 estuary. In the period during which the great 

 masses of London clay were deposited, the site of 

 London must have been near the mouth of a great 

 river. The mud brought down by this river was 

 piled up on the spot where London now stands, 

 and, from the remains of animals and plants 

 floated down and finally covered over by the sedi- 

 ment which fell upon them after they had sunk to 

 the bottom, we can gain some idea of the character 

 of the surrounding land. From these indications 

 it is evident that the climate must then have been 

 tropical or sub-tropical ; the fish whose traces have 

 been discovered were chiefly sharks, whilst bones 

 of turtles and portions of crocodiles and birds 

 have been preserved. It has been estimated that 

 the sea existing at the time of the deposit of the 

 London clay may have been about 600 feet deep. 

 The upper portions of the deposit indicate a 

 shallowing of the water, and it is in the higher 

 portions that most of the traces of terrestrial 

 vegetation and reptilian and other animal remains 

 have been found. The reptiles were noticeably 

 different from those of the preceding period of 

 the Chalk. An immense interval of time must 

 have elapsed between the dates of the marine 

 conditions represented by the chalk and by the 

 clay. The trees on the land adjoining the London 

 basin were such as must have flourished in a 

 sub-tropical climate. The chief place of the 

 occurrence of these plant remains is the Isle of 



Sheppey, and fossil 'fruits, seeds, and leaves of 

 numerous species have there been found, such as 

 magnolia, eucalyptus, etc. Amongst the mammals 

 which existed round the sea-margin, several 

 tapirs have been found. The remains of an 

 opossum and a bat have also been discovered 

 These carcasses must have been carried out to 

 sea by the current of the great river which 

 transported so many of the plant remains. 



During the periods which succeeded that in 

 which the London clay was deposited, the district 

 of the South of England formed a land surface, and 

 there are no records on the spot to show the vicissi- 

 tudes of succeeding changes. The country was then 

 inhabited by various highly developed animals, 

 including the huge mastodon. During the course 

 of the time which elapsed between the last deposits 

 beneath London and the present period, the almost 

 tropical climate changed, and gave place to one of 

 extreme cold. The great ice-sheet which covered 

 nearly the whole of the northern portion of our 

 country did not extend so far south as London, 

 though it touched the hills bounding the London 

 basin on the north, extensive tokens of the glacial 

 drift having been found at Muswell Hill. After 

 the glacial period, continued upheaval raised the 

 level of the land and the sea-bottom till Britain 

 was united to the Continent across the plain of the 

 North Sea and the valley which now forms the 

 English Channel. At this time the rivers of 

 Britain were probably tributaries of larger ones 

 traversing the continent of Europe. Later, another 

 general subsidence of the land took place, which 

 separated England from the mainland, and left the 

 boundaries of our island of the same general form 

 which they retain at present. The climate 

 gradually grew warmer after the glacial epoch, 

 but the profusion and variety of animal forms 

 which existed in our island previous to that cold 

 period, and were destroyed by the frozen con- 

 ditions, never returned. 



7, Mountview Road, Crouch Hill, London, N, ; 

 January, 1896. 



Prehistoric Human Remains. — In the public 

 museum of the town of Le Puy, in Auvergne, a 

 block of volcanic breccia is preserved, in which 

 portions of two human skulls are imbedded. They 

 are of the same reddish brown colour as the rest of 

 the material, which is hard but brittle. The frontal 

 bone of one skull is exposed and is small and 

 narrow, but not receding, and not remarkable in 

 development in any way. These relics were got in 

 the course of excavations in a quarry of that 

 material near the town, at the foot of a low cliff, 

 the material of which shows hexagonal columnar 

 stratification like that of the Giant's Causeway. 

 Seeing that the volcanoes of Auvergne have been 

 extinct long ages ago, though geologically speaking 

 of recent date, it is curious that no reference to this 

 interesting find is made by writers on the subject 

 of the antiquity of man. — W. F. De V. Kane, 

 Drumreaske House, Monaghan, Ireland. 



