4 
NATURE NOTES 
We require to know where these are to be found, how they 
got there, what is the scenery peculiar to each, and of what 
uses are these rocks to man respectively. 
(i) Arenaceous. — Sand and gravel are familiar to all, espe- 
cially along our eastern, south-eastern, and south coasts, 
where the beach is obviously the result of the sea wearing 
down the chalk-cliffs from which the flint-stones — seen in 
horizontal rows in chalk-quarries — drop out, are broken up and 
rounded by the waves, the fragments being again and again 
broken and rounded, till they are too small to break any more, 
when they become sand, composed of smooth and rounded 
grains. 
If sand in the course of ages hardens by pressure, it be- 
comes sandstone, as at Hastings, where this rock is again be- 
coming a sea-beach by the action of the waves. 
But a great deal of sand and gravel is made by rivers. 
These have not the force of great waves on a beach, so that the 
sand is “ sharper,” and is much used in making concrete and 
mortar. A good example of the old Thames gravel is seen in 
the cutting near Acton ; and if the reader will look on the north 
side he will notice how the layers of sand and gravel or clay 
lie at various angles instead of being all horizontal. This is in 
consequence of little currents in the water changing their direc- 
tion, possibly by the action of the wind, at the time they were 
deposited in shallow parts. It has been called “ false bedding.” 
Underneath the gravel is the London clay, some hundred and 
more feet thick. This prevents the water from escaping ; and 
the gravel, acting like a sponge, stores it up. Before the water 
companies were established, London was supplied with water 
from wells sunk in the gravel ; and consequently no houses were 
built beyond the furthest extent of gravel on either side of the 
Thames. Thus Marylebone Road on the north, and Brixton 
on the south, were the limits in those directions. 
Now, whenever you see a gravel pit in the country away 
from the sea, you may be pretty sure it was due to the nearest 
river. 
You may have noticed that rivers, as they approach the sea, 
run through broad and flat valleys, such as that seen on either 
side of the Thames on travelling to Reading. Sometimes valleys 
are miles in width, in which the river curves about. Such is 
called an “alluvial plain,” and is entirely due to the gravel, sand 
and clay spread over it by the water, when it was much more 
extensive than now. 
The Fen-country of Lincolnshire and Cambridgeshire is 
entirely due to the sluggish rivers of that part of England. The 
“ fall ” being very slight, the materials brought down from the 
interior of the country got deposited too soon, instead of being 
swept out to sea ; so that the rivers “ silted ” up, and the water 
was thrown back and overflowed the country. Thanks to 
artificial drainage the fen-land is now nearly all recovered, 
cultivated and inhabited. 
