608 REPORTS OF THE BUILDING COMMITTEE. 



After the inspection of the Baltimore marble quarries, I proceeded, according to 

 instructions, to the Point of Bocks, to examine Mr. McGlauchren's quarries. 



I found them situated on Hook's run, two and a half to three miles west of the 

 Point of Bocks, or about seventy-three miles from Baltimore, embraced in highly 

 disturbed, contorted, and deranged chloritic and talcose schists, and distant only 

 about three miles from the brecciated Potomac marble formation. 



Nothing but hand specimens, and a few surface rock for making lime, have been 

 as yet procured here, so that there is but little opportunity of judging the extent of 

 the formation. The surface indications are not favorable, neither as regards uniform- 

 ity of texture and composition, nor yet extent of beds. 



The chloritic schists dip here at a high angle to the south. The out-crop of the 

 white calcareous rock in question lies at the base of a hill on Hook's run, about 

 twenty to twenty-five feet high, and pitches at an angle of some forty-five degrees 

 into the base of the hill, which is here on a level with the bed of Hook's run, at the 

 same time inclining to the west, so that it is inaccessible except at great expense of 

 labor. 



There is a somewhat better exposure of the Hook's run marble at a little higher 

 level, on a hill a few hundred yards to the south ; and here the best specimens were 

 procured ; see No. 15. Part of the ledge is composed of white calcareous layers, 

 which are said to be susceptible of a polish. The rock at both places has a ragged, 

 irregular, and uneven fracture, and is so interspersed with white and green talc, that 

 it cannot be considered of much value as a building-material. It is possible that be- 

 neath this a purer and better rock might be reached ; but the surface indications do 

 not even favor that conclusion. Unless the bed should be brought to the surface by 

 an upward turn of the contorted strata on the south side of this range of hills, there 

 is no possibility of getting at it. Mr. McGlauchren intends to try, if possible, to 

 open a quarry, with a view to ascertain more satisfactorily the extent and quality of 

 this material. 



On the whole, in its present situation, this marble seems worthless for the present 

 purpose. 



During the examination of structures and monuments of Baltimore marble, both 

 in Green Mount cemetery and in the city of Baltimore, with a view to ascertain the 

 durability and facility of working this material, I was so much struck with the beauty 

 of some of the granite vaults and fronts of buildings that I determined to visit the 

 quarries from whence this material was procured, more especially as the owner, Mr. 

 Green, informed me that he was confident he could furnish it at a cheaper rate than 

 the white marble could possibly be supplied, and as it was only two miles out of my 

 way in returning from the Point of Bocks. 



Accordingly, I stopped at Wookstock, 16 miles beyond the Belay House, and 

 inspected carefully the Waterville branch and the Pox rock quarries in this vicinity ; 

 both of which are well opened, and afford a good opportunity of judging the quality 

 and extent of this formation. 



For about a mile square at this locality is an outburst of quartzose granite of 

 magnificent quality, both as regards beauty of appearance, compactness of structure, 

 and uniformity of color, texture, and composition. I have never seen anything 

 superior in this country ; indeed, I doubt whether it can be excelled in any country. 

 The proportion of feldspar and mica is very small. The former is only in minute 

 specks, the latter is small black scales, whilst the great bulk of the rock is a vitreous 

 quartz. 



In consequence of the mica being only in small regular disseminated flakes, it 

 imparts to the rock an agreeable light gray, well adapted, in my judgment, to the 

 Norman style of architecture. 



In consequence of the composition and texture of this granite, it must possess a 

 durability not to be surpassed by any building-material. For the same reason, it 

 must be difficult and expensive to cut ; but in consequence of the precision with 

 which it splits, not only in the lines of cleavage, but even across the grain, it may 

 possibly be furnished in competition with marble. 



To give some idea of the remarkable facility with which the granite in question 

 cleaves, I may state the following facts, which came under my observation : A slab 

 twenty feet long and one foot square was split longitudinally into two, nearly as 

 accurately as if it had been sawed. 



Again, I observed two slabs — one measuring thirteen feet long, four feet six inches 

 broad, and two feet thick ; the other eleven feet long, six feet broad, and two feet 

 thick — which were split in two, so as to form slabs of the same dimensions in length 

 and breadth , but only one foot thick ; and so perfect were the faces of cleavage, that 

 they did not deviate one inch from a true level surface. 



