20 
T. E. LONES-POST-TEETIAKY BEDS. 
traced to their parent deposits, was laid down, in all probability, 
under conditions very similar to those under which bed No. 4 was 
deposited. It is very probable that during the time which elapsed 
between the redistribution of the drifts so as to form bed No. 5, 
and the deposition of the upper part of bed No. 3, the ancient 
river was gradually cutting its way deeper and deeper into the 
valley, and, in consequence of a diminution in the rainfall, becoming 
less powerful and less subject to violent floods. 
This may be regarded as a general account of the probable 
physical history in recent geological times of that part of the Colne 
Valley which lies between Watford and Bushey Mill Lane. 
