142 PREHISTORIC EUROPE. 



deposited gravel in lines at the bottom. But at each succeeding 

 autumn, when the running- water failed, I imagine that the lines 

 of drainage would have been filled up with blown snow, after- 

 wards congealed ; and that owing to the great surface-accumu- 

 lations of snow it would be a mere chance whether the drainage, 

 together with gravel and sand, would follow the same lines 

 during the next summer. Thus, as I apprehend, alternate 

 layers of frozen snow and drift in sheets and lines would ulti- 

 mately have covered the country to a great thickness, with lines 

 of drift probably deposited in various directions at the bottom by 

 the larger streams. As the climate became warmer the lower beds 

 of frozen snow would have melted with extreme slowness, and 

 during this movement the elongated pebbles would have arranged 

 themselves more or less vertically. The drift would also have been 

 deposited almost irrespective of the outline of the underlying 

 land. When I viewed the country I could not persuade myself 

 that any flood, however great, could have deposited such coarse 

 gravel over the almost level platforms between the valleys." 



Mr. Darwin writes me again recently to say that subsequent 

 observations near Southampton and elsewhere have only tended 

 to strengthen him in his conclusion. Referring to the structure 

 of his own neighbourhood (Beckingham, Kent), he says the chalk- 

 platform slopes gently down from the edge of the escarpment 

 (which is about 800 feet in height) towards the north, where it 

 disappears below the Tertiary strata. " The beds of the large and 

 broad valleys, and only of these, are covered with an immense 

 mass of closely-packed, broken, and angular flints, in which mass 

 remains of the musk-sheep and woolly elephant have been found. 

 This great accumulation of unworn flints must therefore have 

 been made when the climate was cold, and I believe it can be 

 accounted for by the large valleys having been filled up to a great 

 depth during a large part of the year with drifted frozen snow, 

 over which rubbish from the upper parts of the platforms was 

 washed by the summer rains and torrents, sometimes along one 

 line and sometimes along another, or in channels cut through 

 the snow all along the main course of the broad valleys." 



