GEOLOGY. 3 
Chalk is seen close to the surface in the railway cutting at 
St. John’s Station. It also occurs at the surface between the south 
side of Blackheath Hill and the east side of the Lewisham Road. 
We now leave the Secondary and enter the Tertiary or 
Cainozoic Period. This is thrice divided into Eocene (the lowest 
portion), Miocene, and Pliocene. In our district we have only 
to do with the lower Eocene formation, comprising:—(1) The 
Thanet beds; (2) Woolwich and Reading beds; (3) Oldhaven and 
Blackheath beds; (4) The London Clay. The three first-named 
are generally spoken of as the Lower London Tertiaries. 
In our district the Thanet beds are represented by a white 
sand which is a marine formation, and contains in its lower 
PLATE 1. 
portion numerous glauconitic granules. Until recent years fine 
sections of this sand existed in the brick-fields off Loampit Hill. 
On the west side of the railway cutting close to the London 
side of St. John’s Station, there is a gap in the chalk about 4ft. 
wide, due to a ‘‘fault,” which is filled in with Thanet sand. In 
the cutting at and near Swanley Junction it is well shown, also in 
a lane at the side of ‘*The Sandrock” Tavern on the Shirley Hills. 
In 1906 the grounds of an old mansion at Belmont Hill were 
laid out as a building estate. In the excavations made for cutting 
out roads a fine section of Thanet sand was disclosed, which is 
shown in Plate 1, reproduced from one of a series of photo- 
B2 
