.894-] 255 [Shaler. 
cretions may often be observed in positions where they are no 
longer growing, in cliambers into which the waters long failed to 
enter. They are sometimes found with thick deposits of cavern 
dust lying beneath their dependent masses, showing clearly that the 
waters which formed them have long since ceased to contribute 
to their masses. The great length of these stalactites, taken in 
connection with their ponderous weight and the ease with which 
they are riven with a strain, makes them excellent indications as 
to the absence of seismic action. There are many caverns in 
Kentucky, Virginia, and elsewhere, which contain in their stalac- 
tites evidence that the earth about them has never been violently 
shaken since the caves were formed. Were it not for the foct 
that we cannot determine in any case, with near approximation to 
truth, the length of time which has elapsed during which these 
masses have escaped seismic action, they would be valuable data 
for reckoning the immunity of the region from eartdquakes. As 
it is, they can be taken only as tolerably general indices of a long- 
continued exemption from great shocks. In none of the scores of 
American caverns which I have explored are fallen stalactites of 
large size at all common, and in all of those which I have had a 
chance to examine it seems likely that the falling was due to a 
giving away of the rock to which they were attached through 
gravitative action alone. In the caverns of Kentucky, Tennessee, 
and Virginia, we find tolerably clear indications that for a very 
considerable time, perhaps for some thousands of years, there has 
been no movement sufficiently violent to give these great masses 
anything more than the slightest motion. I am of the opinion that 
a shock having a horizontal movement as great as that which 
occurred at Charleston would biing a large part of these struc- 
tures from their places on the ceiling to the floors of the caverns. 
It is hardly necessary to state that these several evidences of 
exemption from serious earthquake shocks can be found in but 
few parts of any country. It is only where we have a topo- 
graphy characterized by strong reliefs or where caverns with 
extensive stalactites occur that any determination appears possible. 
Nevertheless from existing scanty data, it appears to me that 
we may affirm an exemption from earthquakes of many extended 
districts in North America. The whole of the Appalachian belt 
gives us one or the other of the proofs which contraindicate 
the action of earthquakes of more than moderate severity since 
