268 DE. A. GILLJGAX OX THE PETEOGEAPHY UP [vol. lxxv, 



established bej'ond doubt. For this purpose, both chemical and 

 spectroscopic tests were made. The grains are generally rounded, 

 though a few of fairly-good crystal outline occur. Often it is 

 clouded with brownish alteration-products. 



Its presence has now been determined in man}' of the beds of 

 the series from the Kinderscout Grit to the Rough Rock. 

 Nowhere, however, has it been found in such abundance as in the 

 garnetiferous layers of the Rough Rock at Cragg Hill Quarry, 

 Horsforth. 



I think it desirable here to point out that I have paid visits to 

 the Cragg-Hill and Whitehall Quarries, Horsforth, much more fre- 

 quently than to any other locality, on account of their proximity 

 to my home ; also that, by having them under such close observa- 

 tion, I have been enabled to discover here the garnetiferous layers: 

 they may occur in just as great abundance elsewhere. I am con- 

 vinced, therefore, that exact statements regarding the abundance 

 or otherwise of minerals in sedimentary deposits must be made and 

 received with caution, unless such statements refer to a succession 

 of beds in a quarry-face, section, or borehole, or where horizons 

 can be definitely correlated. For example, these garnetiferous 

 layers which have yielded such an abundance of heavy minerals are 

 from a quarter to half an inch thick, and, unless a careful watch 

 had been kept upon the material that was being quarried and 

 worked, I make bold to say that they would never have been found. 

 At the present time, when the Cragg-Hill Quarry is not being 

 worked, it is absolutely certain that no one could discover these 

 layers on the quarry -face, and an average specimen of the grit 

 would yield a totally erroneous result regarding the amount of 

 heavy minerals, as I have computed that a garnetiferous layer is 

 about 500 times as rich in heavy minerals as the normal grit. 



It seems to be better for the present purpose to state the 

 results, not in order of abundance only, but in a more general way 

 with regard to the minerals present : — 



(1) in the different lithological types of beds examined ; 



(2) in the succession of beds examined ; 



(3) in separations from various localities. 



(1) The different lithological types of beds may be 

 arranged as follows : — 



(a) Coarse grits and conglomerates containing pebbles half an inch or 

 more in diameter: these yield chiefly — garnets, ilmenite and leucoxene, 

 tourmaline, monazite, magnetite. 



(6) Grits containing no pebbles more than half an inch in diameter : 

 these yield — garnets, ilmenite and leucoxene, tourmaline, monazite, rutile, 

 magnetite. 



(c) Grits containing no particles more than a quarter of an inch in 

 diameter : these yield — garnets, ilmenite and leucoxene. tourmaline, 

 monazite. rutile, zircon, magnetite. 



(d) Sandstones, with grains about an eighth of an inch and less in 

 diameter : these yield — garnets, zircons, rutile, tourmaline, monazite, 

 ilmenite and leucoxene. magnetite. 



