Objections of 
Dr. Boué 
considered. 
184 Professor Sepawick on the 
effects, I should conclude (as I have already done on other evidence) 
that many of the phenomena in High Teesdale, have been pro- 
duced by the chemical action of the Whin-Sill. 
Before I conclude the details of this section, I think it proper 
to notice some remarks of Dr. Boué, in his Essai Géologique 
sur I’Ecosse. He admits the igneous origin of all trap rocks: of 
the class I have been describing, but in almost every instance 
denies the fact of their having modified the beds with which they 
are in contact. I am not sure that I comprehend his theoretical 
views connected with this subject: but in speaking of a series 
of beds in character exactly similar to those which are found 
close to the trap in High Teesdale, he says, that some of them 
may perhaps have been formed by a deposit of volcanic matter 
suspended in a liquid (“‘formées peut-étre par un dépét de matiéres 
“* volcaniques suspendues dans un liquide,” p. 246.) It is unques- 
tionably possible that the waters might have become turbid in 
the vicinity of a submarine eruption of lava; and that the suspended 
particles might afterwards have formed a peculiar deposit. But 
such a deposit could never consist of alternating beds like those 
in High Teesdale, of pure limestone containing, in every part of 
its mass, organic remains of the same kind with those which are 
found in the ordinary strata, of hard siliceous sandstone, and 
of hard argillaceous and siliceous slate with organic remains 
and with layers and nodules of iron-stone. The supposition of 
Dr. Boué is not only gratuitous, but utterly madequate to the 
explanation of such phenomena as are detailed in this Paper. 
In regard to certain substances, which, from his description, 
appear to resemble parts of the indurated shale in contact with 
the Whin-Sill, he states his opinion in the followig words: 
“ Leur fusibilité et leur degré de dureté suffisent pour les distin- 
euer du schiste siliceua ou lydien de Werner, qui leur ressemble 
au premier abord ; leur dureté et leurs autres caractéres empéchent 
