230 



ON THE LEA VALLEY. 



plateaux and at the same time filled up more or less completely 

 the Pre-Glacial valleys. In the Boulder-clay at Hornchurch 

 near Romford, about loo feet below its usual level, thereabouts, 

 yet covered by some of the oldest gravel of the present Thames 

 there is a certain approximation to coincidence, in the valleys of 

 the two periods. Where Post-Glacial drainage has taken a new 

 course, the position of an old Pre-Glacial valley may remain un- 

 suspected but for a well boring, as at Newport Grammar School. 

 Where there is a local coincidence between the Pre-Glacial and 



Post-Glacial valleys, there we may find a fragment of a Pre- 

 Glacial channel filled with material of Glacial age beneath river- 

 deposits of later date, as at Littlebury and the Lockwood 

 Reservoir. But of course both channels alike suggest that 

 during their formation the whole country stood at a much higher 

 level above the sea than it now does. For in each case the 

 bottom of the channel is below the present level of the sea. 



The photograph is one taken by Mr. F. Meeson during the 

 visit of the Geologists' Association m April, igoi. The spectator 

 is looking southward, and the view gives the section across two 



