16 BOROUGH OF LEWISHAM. 
irregularities which now appear are due to subaerial erosion by 
streams now long extinct, and by the snows and frosts of winter, 
and the rains and droughts of summer. Where the clay has 
offered the least resistance it has been removed; where it is harder 
it has remained, and thus we have ai undulating surface. Denuda- 
tion of this description is ever in process, but so slowly that it 
escapes observation. Every fall of rain dissolves out or washes 
away a certain amount of earthy matter which ultimately reaches 
the sea. It is not lost. There will be in the future, as there has 
been in the past, upheavals, and that which the land now loses will 
in some distant epoch help to form new islands and continents, 
which may peradventure be inhabited by Tennyson’s ‘‘ Crowning 
race” 
‘Of those that eye to eye shall look 
On knowledge; under whose command 
Is Earth and Earths, and in their hand 
Is Nature like an open book.” 
