302 Richard Adie on the Influence of 
high-water mark by the effect of the sea breezes. If we 
come to consider the relative strength of land and sea winds, 
the preponderance of force will always be in favour of the 
latter, for they are unchecked by objects, like arboreal vege- 
tation, which the land-winds encounter. After they cross 
high-water mark, the respective character of the two changes ; 
the land-breeze there makes its escape from the obstacles 
which reduced its force, while the sea-breeze at the same 
point begins to encounter them. Thus, if the land and sea 
winds on a coast are supposed to be of equal duration through- 
out the year, the greater force of the latter would leave an 
excess of sand above high-water mark; which is the case 
which occurs in nature. When the shores of Liverpool bay 
are viewed from a little distance, they appear to be skirted 
by a ridge of sand of from twenty to fifty feet high. This 
ridge nearer hand is found to be not continuous, but to 
have gaps at intervals, through which the ground in- 
land may be reached without ascending more than a few 
feet. These gaps appear to me to serve the purpose of per- 
mitting the wind to escape with less resistance than if the 
sand had formed an undivided ridge. The phenomenon of 
the formation of sand-hills on parts of our coasts which sup- 
ply the requisite conditions, can be explained by viewing them 
as the forms of least resistance the wind has arranged sand 
it has brushedup from the beach,and over which it has to cross. 
The dome or conical hill is the type of the form of least resist- 
ance, which in our climate is much modified by vegetation’ 
through the roots and stems of plants binding the sand. In 
Liverpool bay, the belt of sand-hills is broadest in the neigh- 
bourhood of Formby Point, where the flat character of the 
country inland offers slight impediments to the progress of 
the wind; they attain the height of fifty feet, and the specific 
gravity of their materials agrees exactly with that of the ad- 
joining beach, namely, 2:58. 
A friend of mine, who has examined the sand-hills on the 
coast of Brazil, informs me that on the northern part of that 
coast domes of pure sand rise to the height of 150 feet. 
Their superior elevation in that place he accounts for by the 
steady regularity of the sea-winds and the dry nature of the 
