510 H. HICKS ON THE PRE-CAMBRIAN 
whole interpretation of the Survey map in the immediate neigh- 
bourhood of St. David’s; therefore it was but natural that the 
Director-General should, as stated in his paper, before “ admitting 
corrections of the views expressed upon the maps and sections of 
the Geological Survey,” only do so after an “ actual inspection of 
the ground” *. 
Ill. Dr. Gerxte’s Conciustons. 
The object of his paper communicated to the Society is stated by 
Dr. Geikie at p. 266, to be ‘“‘ twofold—first, to discuss the evidence 
for the assertion that Pre-Cambrian rocks exist at St. David’s, and 
secondly, to lay before the Society an outline of what appears” to 
him “to be the true structure and geological history of that district.” 
Tn his conclusions at p. 291, he gives the main results of his re- 
survey in the following words:—‘“ As the result of my resurvey, lL 
find that the true meaning of the volcanic group at the bottom of 
the Cambrian strata there exposed, though partly recognized in the 
first edition of the map and section, had been subsequently lost 
sight of, these rocks having been erroneously renamed by the Survey 
‘ Altered Cambrian,’ with intrusive sheets of ‘greenstone.’ I have 
freely admitted this to be an important error.” <“ Again, were the 
area to be resurveyed now we should not colour as one continuous 
belt of intrusive rock the long strip of country from the coast near 
St. David’s north-eastward to beyond Llanhowell. We should 
endeavour, as far as possible, to represent only those portions of 
eruptive rock which are actually visible or unquestionably exist 
underneath the surface, leaving the intervening spaces on the map 
to be coloured with the tint used for the general stratified formation 
of each area. We should prefer to indicate in this way that there 
are detached dykes and bosses along a certain area of extravasation, 
rather than to map the whole as one continuous belt. But this 
would be, after all, a question of detail or style of mapping. ‘The 
officers of the Survey were certainly correct in regarding the crys- 
talline rocks, which they named syenite and felstone, as intrusive 
through the Cambrian strata; and this is the main question in the 
present discussion. In concluding this part of my paper I am 
bound emphatically to declare that the map of the St. Dayid’s dis- 
trict, as surveyed by De la Beche, Ramsay, and Aveline, is in its 
essential features correct.” 
LV. Some oF THE Matin D1FFERENCES BETWEEN OUR VIEWS. 
I wish especially to call attention to the last two paragraphs 
quoted above, for they certainly touch the very essence of the dis- 
agreement between my own views and those of the officers of the 
Survey. In those paragraphs it is maintained that the granitoid 
rocks, their former syenite (our Dimetian), are intrusive in the 
Cambrian rocks. I hold, on the other hand, that they are the oldest 
* Ibid. p, 261. 
