vi PEOCEEDIIS^GS OF THE GEOLOGICAL SOCIETY. [vol. Ixxviii, 



nortli 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 dr}^ health}' soil and an 

 easily accessible water-supply ; they crowned twin hills separated 

 by the deep valle}' of the Walbrook, bounded on the east b}^ the 

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

 the west by the steep descent to the Fleet ; the site was, therefore, 

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

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

 the river ; the most ancient embankment la}" 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 Eoman encampment lay east of 

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

 w^as worked. Later the city expanded, until the St. Paul's hill 

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

 century. The great Poman road from Kent (Watling Street) 

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

 minster — on its way to Yerulamium and the north-Avest. The 

 earliest Westminster was a Poman 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, w^as 

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

 road at Hyde Park Corner, running along the ' Strand," where the 

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

 gravel by the London Clay was utilized for the Poman 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 Domesda}'- 

 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 largel}" b}" the damming 

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

 London and Westminster are ' connected b}^ 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 sloAvly, 

 but in the second half of the 17th centur}" with great rapidit}^ 

 By the end of that period the whole of the area covered b}" 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 

 provided the water-supply. In earh^ days the City was dependent 

 on many wells sunk through the gravel, some of which were famous, 



