300 
EXPLANATION OF GEOLOGICAL FACTS, 
the natural dark colour imbedded in the mixed mass, and if he 
subjected them to the most accurate measurement, he would find 
their edge and angles corresponding. If he should leave the Table 
Mountain and visit Green Point, where the mixture of the two 
rocks is more intimate, he would still have to contend with facts 
scarcely explicable on the Neptunian theory. The appearance 
most likely to arrest his attention, would be the intimate inter- 
mingling of the two rocks in the large field, a portion of which is 
represented in page 289., and which he would probably consider, 
on a first view, not only explicable on the theory of aqueous form- 
ation, but as favourable to it. Here he could see that intermingling, 
and wedging, and gradation of one rock into the other, which his 
opinions require. But this conclusion would perhaps give way to 
a wider view of the phenomena around him. The leading feature 
stamped on all the facts at Green Point is exceeding commotion at 
the period of the mixture of the.two formations. To conceive that 
they were deposited from a fluid in a state of rest, seems to me im- 
possible for any one crediting the evidence of sense. Although it 
might perhaps be said, that their intimate mixture was the conse- 
quence of the agitation of the fluid whilst they were crystallizing. But 
supposing a Neptunian to have formed this inference, he must, I appre- 
hend, yield it to one of the conditions of his own theory, and one of the 
laws of crystallization.* Bodies of a perfect crystalline structure can 
only be formed as a chemical deposit from a fluid in a state of rest. 
Rocks of an earthy fracture are formed from a fluid more or less 
agitated. What then are the characters of the rocks at the point of 
* “ We know the conditions necessary for the formation of a crystalline structure, and 
that rest and motion are the agents which assist or prevent its regular formation. Hence 
we may very fairly infer that the solution or ocean when it stood high over the earth was 
calm and undisturbed. During succeeding periods the solution appears to have become 
more and more agitated; yet at first it only prevented the perfection of the crystallization. 
As the water diminished in height its motions increased ; its destroying powers reached 
to the surface of the earth and the crystalline shoots were destroyed, and thus the first 
mechanical productions were formed.” Elements of Geognosy, p. 90. 
