106 CORAL FORMATIONS. 
idea of the force of the lifting wave ; and there are examples on record, 
to be found in various treatises on Geology, of still more surprising 
effects. * 
We must, therefore, allow that some effect will be produced upon 
the coral groves. There will be trees prostrated by gales, as on land, 
fragments scattered, and fragmentary and sand accumulations com- 
menced. Besides, masses of the heavier corals will be uptorn, and 
carried along over the coral plantation, which will destroy and grind 
down everything in their way. So many are the accidents of this 
kind to which zoophytes appear to be exposed, that we might believe 
* Lyell, vol. ii. p. 38-40. Speaking of the force of waves on coasts, Lyell mentions 
the transportation of a block of stone, ninety feet from its bed, which was eight feet two 
inches, by seven feet, and five feet one inch, in its dimensions, and another nine feet two 
inches, by six and a half feet, by four feet, which “ was hurried up an acclivity to a dis- 
tance of one hundred and fifty feet.” 
In an article on this subject, by Thomas Stevenson, of Edinburgh, published in the 
Transactions of the Royal Society of Edinburgh (vol. xvi., 1845), it is stated, as a de- 
duction from two hundred and sixty-seven experiments, extending over twenty-three suc- 
cessive months, that the average force for Skerryvore, for five of the summer months, 
during the years 1843, 1844, was six hundred and eleven pounds per square foot ; and 
for six of the winter months of the same year, it was two thousand and eighty-six pounds 
per square foot, or three times as great as during the summer months. During a westerly 
gale, at the same place, in March, 1845, a pressure of six thousand and eighty-three 
pounds was registered by Mr. Stevenson’s dynamometer, (the name of the instrument 
used.) He mentions several remarkable instances of transported blocks. One of gneiss, 
containing five hundred and four cubic feet, was carried by the waves five feet from the 
place where it lay, and there became wedged so as no longer to be moved. Of the 
manner in which it was moved, Mr. Reid (as cited by Mr. Stevenson) says: “ The sea, 
when [ saw it striking the stone, would wholly immerse or bury it out of sight, and the 
run extended up to the grass line above it, making a perpendicular rise of from thirty- 
nine to forty feet above high water level. On the incoming waves striking the stone, we 
could sce this monstrous mass, of upwards of forty tons weight, lean landwards, and the 
back-run would uplift it again with a jerk, leaving it with very little water about it, when 
the next incoming wave made it recline again.” 
Mr. Stevenson states also that the Bell Rock Lighthouse in the German Ocean, though 
one hundred and twelve feet in height, is literally buried in foam and spray, to the very 
top, during ground swells, when there is no wind. On the 20th of November, 1827, the 
spray rose to the height of one hundred and seventeen feet above the foundations or low 
water mark ; and deducting eleven feet for the tide that day, it leaves one hundred and 
six feet, which is equivalent to a pressure of nearly three tons per square foot. 
With such facts, any incredulity respecting the power of waves should be laid aside. 
Moreover, it may be remarked that the Pacific is a much wider ocean than the Atlantic, 
with far heavier waves in its ordinary state. 
