ripplebox the sand is kept in a loose state 
and the gold easily falls to the bottom. rmt 
if at anv time owing to a stoppage in the. 
supply of fresh material the water becomes 
clear the sands quickly sets or hardens and 
if then fresh material is brought in and 
the water becomes muddy again the gold 
does not sink into the material in the ripple- 
box, but it and the gravel and sand are 
carried off over the surface ol the former 
deposit. Clear water, therefore, causes the 
settlemeot of gravel and sand while muddy 
water keeps it loose and in an active and 
lively state, greatly promoting the rapidity of 
removal. The cause, of course, is the greater 
specific gravity of muddy water, the gravel 
and sand consequently almost Moating in it 
and being thereby rapidly moved onwards by 
he current. Such accidents as the San 
Francisco and .Jamaica earthquakes, as well 
as those which have occurred on the west 
coast of South America, are in part—at least 
—due to subsidences and dislocations of poi’- 
tionsof the earth's crust, largely produced, no 
doubt, by the removal of portions of matter 
from one place to another, chieMy caused by 
rain and rivers, although possibly also by 
withdrawal of molten material beneath or in 
the crust of the earth. Thus you see that 
the enormous mass of matter which has by 
the operations of denudation been removed 
from these valleys arid deposited somewhere 
else must have caused a disturbance of 
equilibrium just as happens when you remove 
a weight from one scale of a balance and 
place it in the opposite one. But all sucb 
accidents are naturally more prone to take 
place along lines of weakness in the earth’s 
crust, and such lines of weakness are often 
shown bv dislocat ions, faults and depressions 
below the general level. The Gulf of Sari 
Francisco is situated on such a line of weak¬ 
ness. so also is the harbour of Kingston, 
Jamaica. The south west portion of the 
island of: Haiti exhibits another remarkable 
instance of a line of .veakness whose depres¬ 
sions are shown by several lakes, laguns 
ami bays extending from Bahia de 
Neiba to San Mark channel to the 
north of Go-nave island. Another equally 
obvious line of depression is that which 
•extends from the Bay of Samana in the 
north-east to Bahia de Manzanilla near 
Monte Cristo in the north of the said island. 
.And that this last great depression called 
generally Lave.ga was under water in tertiary 
times is proved by the extensive develop¬ 
ment Of raioceme formations alofig its margins 
with-an extremely rich and characteristic 
