J. D. Dana on the Characters distinguishing Kinds of Rocks. 487 
no fusion to produce the coalescence. As this welding of beds 
is so perfect in the limestone, it is reasonable to believe that a 
similar cause may have acted in the case of feldspathic, horn- 
blendic and augitie rocks, without even the aid of incipient 
usion. 
(4.) The sedimentary beds which have been converted into crystal- 
line rocks were often originally massive.—This is the condition of 
most conglomerates, and often of coarse sandstones. In suc 
cases there would be no bedding to obliterate ; and the produc- 
tion of a massive rock would be a natural result of the meta- 
morphism, whether the heat attending it were great or small. 
Part of the metamorphic granite of the world may therefore 
uever have been in a pasty state ; and so also part of the meta- 
morphic hornblende rocks ; some metamorphic felsyte beds, cer- 
tainly those that are of conglomerate origin, were originally 
massive, ; 
There is hence reason enough for neglecting the distinction 
of massive and schistose in drawing out a system or classifica- 
tion of rocks, and for making the question of origin in the case 
of either kind, the massive no less than the schistose, a subject 
for careful investigation. 
9, Metamorphic or Eruptive-—The question whether a crystal- 
line rock is metamorphic and in place, or eruptive, is of the high- 
est geological interest ; for it is a question as to origin. At the 
same time, no subject, if we exclude the part of metamorphism 
relating to the obviously schistose rocks, is in so unsatisfactory 
a state. With some authors, as above intimated, the question 
so far as it relates to massive crystalline rock is not an open 
one. On the other hand, when investigation has taken place, 
Opposite opinions have generally been reached. The remedy 
of this is to be found in more thorough study from a wider 
basis of facts. 
greater completeness and higher geological value to the descrip- 
tions of rocks, Applying different names to the like rocks in 
metamorphic under any kind of rock by ing to the name 
the prefix meta; for example, dioryte for the eruptive and 
metadioryte for the metamorphic part. But meta is usec 
simply as an abbreviation of the word metamorphic, not to indi- 
cate a difference of kind in the rock. 2 
