Burton: Coast Erosion. Lag k 
of the beach, whether hard or soft or shelving, as well as by 
the set of currents and tides. 
The atmosphere has great crumbling action on soft bedded 
rocks, and they would gradually accumulate as rock debris 
or talus, and be banked up against any cliff exposure and so 
protect it from further denudation, but in the case of shore 
cliffs this protective action is denied them, and waves carry 
away the weather-worn material, and thus atmospheric de- 
nudation is continuous. 
A fault is in itself not necessarily an active agent in wasting 
shore cliffs, but faults usually produce springs of water and these 
are a most prolific source of waste of land. 
Rocks of hard material which will withstand great abraisive 
action, are sometimes composed of such porous or solable matter 
that percolating rain water dissolves some of their constituents 
and gives them a brecciated appearance, and makes them 
peculiarly lable to marine denudation. Magnesian Lime- 
s.one and Chalk, and even the more resisting Mountain Lime- 
stone, come under this head. 
Currents have much to do with erosion, as unless the wasted 
rock material is removed the waste would cease. How some 
curren‘s are formed is not quite easy to explain, but their 
effec’s are visible in such places as Spurn Point, Chesil Bank, 
Dungeness and elsewhere where the travel of beach material 
has been arrested. This travel is curious. Apparently it is 
from north to south between the Tweed and Thames; west 
to east along the south coast up to the Thames; south to 
north along the west coast as far north as Morecambe Bay ; 
then locally, north to south between Walney Island and Work- 
ing on; from there again north round the coast of Scotland 
back to the Tweed. 
Rain water, whether by carrying down the soft surface 
deposits, or by percolating through the hard subsoil and the 
sill harder lower rocks, greatly aids erosion. In the former 
case the action is direct and evident. In the latter it is in- 
direct and inferential, but not lesscertain. The solvent action 
of the water removes certain salts from practically every rock 
through which it percolates, and in the case of Magnesian and 
Carboniferous Limestones and Chalk this action is fairly 
rapid. Under certain conditions the same solvent force is 
equally active in ferruginous rocks. Surface drainage by 
cu’‘ing down the land surface until it reaches sea level is 
another continuous cause of coast erosion. 
A laminated and jointed shale beach is peculiarly liable to be 
brok nup, and as the breaking up process proceeds the waves 
reach further inshore with greater force. The converse is true. 
Erosion is greatest around our shores (a) where the shore 
cliffs consist of masses of boulder clay, sand and gravel, or 
1915'April 1 
