15S 



the red sandstone of the district of no value. As this section of 

 the country is not well supplied with building stone capable 

 of withstanding the weather, the hint that durable varieties 

 abound near the trap ridges, may prove of service. From what 

 has been said, it will be seen that the most probable position for 

 the better kinds, is neither too near the trap nor too remote from 

 it, but is indicated by the amount of baking, which the rock ap- 

 pears to have undergone. This should not be too great, lest the 

 rock be very hard and difficult to cleave into regular blocks; 

 nor yet too little, as it will be then soft enough to be operated on by 

 the frost. When a rather compact and extremely durable kind 

 is sought, I would suggest that it will usually occur within one 

 or two hundred feet of the trap, and may be known by a bluish 

 or dull purple colour, and by a multitude of dim round spots, the 

 commencement, as it were, of the crystalline nodules. On the 

 other hand, when a rock of rather softer variety, but cleaveable 

 into larger blocks, is desired, then I would propose the beds rather 

 more remote from the trap, where the stone retains a pretty 

 bright red colour, and contains large, fully formed nodules of 

 green epidote. 



It is not asserted that these altered strata will always appear 

 bordering the ridges of trap; but I find them in frequency far 

 greater than might be expected, and their importance therefore, 

 is considerable. By following the base of a range of trap, though 

 we may not at once meet with any rock of that exact degree of 

 induration which we seek, we cannot pursue the search far in 

 the longitudinal direction without falling upon a locality where 

 all the requisite varieties present themselves. Much aid will be 

 derived from inspecting the spots and nodules upon the fragments 

 scattered over the surface of the soil. 



OF THE COPPER ORES OF THE RED SANDSTO^E REGION. 



The ores of copper, especially the carbonate, red oxide, and 

 blue sulphuret, exist in many places in the red sandstone region, 

 though hitherto they have never been procured in abundance. 

 Their position in every case would appear to be contiguous to 

 dikes of trap ; the present seems therefore the appropriate place 

 in which to describe them. 



