﻿Influence of Geology on the History of London. 287 



Continent came by the ports of Kent, and, if destined for the 

 north or east of Britain, sought the lowest possible crossing of 

 the Thames. This was near old London Bridge, where the low- 

 level gravel on the south and the Middle Terrace deposits on the 

 north approached close to the river-bank. A settlement was 

 obviously required here, and the northern side was chosen as the 

 higher ground. The gravels provided a dry healthy soil and an 

 easily accessible water-supply ; they crowned twin hills separated 

 by the deep valley of the Walbrook, bounded on the east by the 

 low ground near the Tower and the Lea with its marshes, and on 

 the west b}' the steep descent to the Fleet ; the site was, therefore, 

 easily defensible. The river-face of the hills was naturally more 

 abrupt than it is now, owing to the reclamation of ground from 

 the river ; the most ancient embankment lay 60 feet north of the 

 northern side of Thames Street. 



The first definite evidence of a permanent settlement was the 

 reference in Tacitus. The early Roman encampment lay east of 

 the Walbrook, and the brickearth on the west around St. Paul's 

 was worked. Later the city expanded, until the St. Paul's hill 

 was included, the wall being built in the second half of the 4th 

 centuiy. The great Roman road from Kent (Watling Street) 

 avoided London, and utilized the next ford upstream — at West- 

 minster — on its way to Yeralamium and the north-west, The 

 earliest Westminster was a Roman settlement beside the ford, 

 built on a small island of gravel and sand between two mouths of 

 the Tyburn. This settlement could not grow, as did London, 

 since the area of the island, known to the Saxons as Thorney, was 

 small. The road from London to the west joined the St. Alban's 

 road at Hyde Park Corner, running along the ' Strand,' Avhere the 

 gravel came close to the river ; a spring thrown out from this 

 gravel by the London Clay was utilized for the Roman Bath in 

 Strand Lane. 



Throughout Mediaeval times London was practically confined to 

 the walled city, a defensible position being essential. The forests 

 of the London-Clay belt on the north are indicated in Domesday 

 Book and referred to by several writers, notably Fitzstephen, 

 whose Chronicle also mentions many of the springs and wells 

 and the marsh of Moorfields, produced largely by the damming 

 of the Walbrook by the Wall. The same writer mentions that 

 London and Westminster are ' connected by a suburb.' This 

 was along the ' Strand,' and consisted first of great noblemen's 

 houses facing the river and a row of cottages along the north 

 side of the road ; this link grew northwards, at first slowly, 

 but in the second half of the 17th century with great rapidity. 

 By the end of that period the Avhole of the area covered by the 

 Middle-Terrace Gravel was built over, but the northern margin of 

 the gravel was also that of the town for 100 years, the London- 

 Clay belt remaining unoccupied. 



The reason for this arrested development was that the gravel 



