470 J. H. COLLINS ON THE SERPENTINE AND 
CoNncLUSION. 
In concluding these brief notes, I would repeat, to prevent misap- 
prehension, that while I do not deny that in some instances, even 
in the Lizard district, masses of highly basic and distinctly intrusive 
igneous rocks may have been altered into serpentine, yet, in this case, 
the evidence is altogether the other way. Careful examination of 
the cliff-sections affords evidence of stratification in the serpentine, 
both on the large and on the small scale, 2. ¢. of the serpentinous 
change of stratified materials in situ; this conclusion is supported 
by the chemical analysis of hand-specimens, as well as by their 
macroscopical and microscopical appearance ; it is paralleled by what 
Prof. Heddle has described of his observations in the Hebrides and 
Aberdeenshire * ; while his theory, which is modified from that of 
Dr. Sterry Hunt, affords a full explanation of the manner of the 
change 7. Furthermore, there does not appear to me to exist any 
reason for referring the numerous contortions which admittedly 
exist in the Porthalla rocks to the introduction of any intrusive 
mass whatever. It seems to me that it is begging the question to 
state that these contortions are due to the intrusion of the serpen- 
tine. Prof. Bonney does not, I believe, attribute the contortions 
to this cause, although Sir H. De la Beche clearly did; for he says 
‘‘We find a mass of serpentine amid the hornblende slate be- 
tween Dranna Point and Porthalla, on the north of the principal 
mass of serpentine, which has every appearance of having been 
thrust up among the hornblende slate, twisting and contorting the 
laminee adjoming it in directions which we should consider con- 
sistent with the passage of the serpentine in a state of igneous 
fusion through them” +. 
If it should be thought necessary to call in the aid of any such 
agent to produce the contortions in question, we have two intrusive 
rocks existing in the immediate neighbourhood, viz. the granulite 
and the gabbro. My own belief is, however, that the contortions 
were produced by an agency far more general, the same which has 
produced the axis of elevation of the south coast of Cornwall in the 
line of the Eddystone, and parallel to the general granitic axis of the 
Cornish peninsula. 
My argument, that we have at Porthalla a “ passage ” from the 
one rock into the other is much strengthened by the fact that many 
such ‘apparent passages” are admitted to exist by all those who have 
examined the Lizard coast with any degree of detail—including Sir 
H. De la Beche and Prof. Bonney. De la Beche’s description of that 
seen near the Lizard Town is as follows, and it would apply equally 
well to the others. ‘The hornblende slate,’ he says, “supports 
the great mass of the Lizard serpentine, with an apparent passage 
* «Chapters on the Mineralogy of Scotland: iv. Augite, Hornblende, and 
Serpentinous change,” Trans. Roy. Soc. Edinb. 1880. 
+ The discussion of this matter, originally contained in my paper, has been 
omitted by order of the Council. 
¢ Report on Cornwall, &., p. 30. 
