File:The Quarterly journal of the Geological Society of London (13205928953).jpg

210
PROCEEDINGS OF THE GEOLOGICAL SOCIETY.
may determine the exit of the melted matter at the nearest points of
weakest resistance.
91. Other consequences might arise from the different fusibility of
the various strata deposited in the bed of the ocean. Let us imagine
in the next woodcut (fig. 5), the two beds A and B to melt at a much
lower temperature than those between which they intervene. It
might happen, by the gradual rising of the isothermal surfaces, that
one or both of these strata should be melted ; and thus, supposing
Fig. 5.
all the beds originally to have contained marine remains, we might,
at a distant period, discover two interposed beds, without any trace
of such remains, but presenting all the appearances of former fusion,
resting on, separated by, and existing under, other beds of demon-
strably marine formation.
If, during that former state of fusion, rents should have been
formed through several of the strata, injection of the liquid matter
might proceed from these melted beds, both upwards and down-
wards. If, on the contrary, older dykes had penetrated all the strata,
it is possible to suppose such a degree of fusibility in the older dyke,
or such chemical relation to the melted bed, that the portions of the
dyke passing through that bed should be obliterated, whilst those that
traverse the less fusible beds, protected from such action, should
remain unaltered, as in the annexed cut (fig. 6).