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SCIENCE-GOSSIP. 



THE SITE OF LONDON. 



By J. J. Stewart, B.A., B.Sc. 



T T is difficult to gain an idea of what must have 

 been the condition of the region now occupied 

 by the City of London in the more remote 

 geological ages, for the earlier rocks are covered 

 over by the great deposit of London clay, which is 

 in many parts several hundreds of feet thick. But 

 certain deep well borings enable us to gain some 

 insight into the conditions which prevailed at this 

 spot of the earth's surface during certain epochs in 

 the long procession of time. From the records 

 left in the deposits laid down when the area was 

 covered by the sea, or by estuaries, we can 

 determine with some probability at what period 

 the region was dry land, and when it lay beneath 

 the waters ; and besides this, the pebbles and 

 debris which have been found embedded in 

 localities near London, and which must have come 

 from the spot on which the city now stands, 

 enable us to judge of the climatic and other con- 

 ditions which held sway at different periods in this 

 region. Amongst the most ancient records that 

 we have are specimens of rock, which, brought up 

 from a depth of over 1,100 feet below the level of 

 the present Oxford Street, indicate that during the 

 Devonian period, or in a portion of that long 

 interval which elapsed between the Silurian and 

 Carboniferous times, the site of London was 

 covered by the shallow waters of the Devonian 

 Sea. During this period coral reefs were numerous, 

 and the shallow lagoons became filled up with 

 muddy sediment. On the land surface, which 

 probably existed to the north of the region we are 

 considering, fern-like plants abounded, and the 

 organisms belonged to the less highly developed 

 types. 



In the succeeding Carboniferous period the south 

 of England seems to have formed part of that 

 extensive basin which stretched eastward over part 

 of France, German)' and Russia, covering a con- 

 siderable portion of the present Continent of Europe. 

 This sea was probably land-locked and resembled 

 the present Mediterranean. In deeper portions 

 towards the North of England great deposits of 

 limestone occurred, produced from the calcareous 

 shells of organisms which inhabited it. To the 

 north-east, over the site of Scandinavia, a stretch 

 of land, forming a large continent, probably existed. 

 Owing to the deposit of sediments, the shallower 

 portions of the Carboniferous sea became silted up, 

 and in the marshes thus formed, the luxuriant 

 vegetation flourished which, on its decay, gave 

 rise to the coal deposits. There seems to be not 

 much likelihood of coal being found beneath the 

 site of London, though coal seams may at one 



time have existed there. During the succeeding 

 geological periods the site of London seems to have 

 been on land, and the erosion and denudation 

 which took place during long ages most probably 

 wore away all the deposits laid down in the 

 Carboniferous epoch. Fragments of anthracite, 

 mingled with pebbles formed from the sandstone 

 of the coal measure period, have been found at 

 Richmond above and below the great oolite, 

 indicating that land with coal measures upon it 

 occupied the region of London while these beds at 

 Richmond were laid down. 



During the ages following the Carboniferous 

 times, the site of London was chiefly dry land. 

 Few records of these periods therefore are found, 

 but the prolonged effect of weather and streams 

 was gradually removing the deposits previously 

 accumulated, and laying them down afresh beneath 

 the waters of the neighbouring sea. 



At the beginning of the Cretaceous epoch, the 

 site of London seems to have been close to a great 

 estuary which formed the mouth of a mighty 

 river. From the fragments of animal remains 

 which have been preserved, and which were 

 drifted down by the river, we learn that on the site 

 of the City must have roamed huge deinosaurian 

 reptiles, living partly on land and partly in the 

 waters of the estuary, some of them being provided 

 with fin-like paddles. Bird-like forms also existed 

 at this time which had great affinities with 

 reptiles. After the long exposure and erosion of 

 previous periods, whilst this district remained part 

 of the land surface there followed, owing to 

 depression of the surface, a long tract of time 

 during which this portion of England was covered 

 by the waters of the ocean, in which the thick 

 deposits of chalk were formed. This ocean 

 covered the greater part of England and nearly 

 the whole of southern and western Europe ; it 

 seems to have occupied two basins, the site of 

 London being in the northern one. On the land 

 surface, which extended itself on the north-west, 

 ferns, cycads, and trees resembling pines 

 flourished, and some of the modern species of trees 

 now began to appear. The sea, which extended 

 over the district we are considering, altered the 

 estuarine character of the south-east of England 

 which existed in early Cretaceous times. It was 

 probably deep, and the thick deposits of chalk 

 formed from the remains of calcareous animals 

 show that this interval must have lasted a long 

 period of time. It has been disputed whether the 

 chalk was deposited in a deep ocean or in shallow 

 seas whose bottom was gradually sinking, as they 



