On Rocks and Minerals from the Karakoram Himalayas. 471 



of crystal building. Also tubes or fibrous cracks are present, 

 arranged generally at right angles to the faces of the garnet. 

 Rather irregular crystalline grains of yellowish staurolite with 

 many enclosures occur ; also irregular grains of magnetite, and 

 numerous little patchy flakes of brown mica. These are all set in a 

 crystalline matrix, consisting of white mica and (apparently) granular 

 quartz, with usually a considerable quantity of opacite (probably 

 graphite), a few small tourmalines (strongly dichroic, changing from 

 a light to a brownish or dull greenish tint), and some small rutiles. 

 A similar schist comes from near Askole, and one without garnets, 

 but in other respects like these, from the south flank of Crystal Peak. 

 The chief interest of these garnet-bearing mica schists is their very 

 close resemblance to schists in the Lepontine Alps,* as described by 

 one of us, where the rock is a local variety of a dark micaceous 

 schist, and it occurs, to his knowledge, at intervals for a distance of 

 over 30 miles in a straight line along the chain. 



With the mica schists we may mention, under the general name of 

 sericite schists, several very much crushed rocks from Kamar nala, 

 Mir, and the Dar Valley, Bagrot, and then pass on to a group of 

 more or less calcareous schists, such as are developed in the Alps, 

 and are there associated with quartz schists, green schists, and the 

 aforesaid black garnet schists. In that chain they not unfrequently 

 pass into crystalline limestones or dolomites, and rocks of this cha- 

 racter also occur in Mr. Conway's collection. One or two contain 

 malacolite, and some show distinct signs of having been affected by 

 pressure .f 



Passing on to the ordinary sedimentary rocks, we find a number of 

 limestones, more or less impure, some containing fragments of other 

 rocks, with schistose calcareous grits, besides argillites and slates, 

 one or two of the latter resembling the slates of Llanberis (North 

 Wales). A few of the specimens contain much crystalline material, 

 so that it is difficult to decide whether they are very crushed dark 

 schists, or slightly altered slates largely composed.of detrital crystal- 

 line material. Rocks may be found in the Alps which present similar 

 difficulties. 



Sandstones, grits, and conglomerates occur ; some of the gritty 

 rocks show a cleavage, and certain near the Golden Throne probably 

 contain volcanic materials. A conglomerate from Mapnun, in the 

 Burzil Valley, contains a fragment of a quartz diorite, which obviously 

 had been already modified by pressure when it was made into a pebble, 

 indicating that in this mountain region, as in the Alps, earth move- 



* T. G. Bonney, ' Quart. Jl. Geol. Soc.,' vol. 49 (1893), p. 105, &c. We are 

 informed by Mr. G. Barrow, F.G.S., that a similar schist occurs in the Central 

 Highlands of Scotland. T. G. B. 



t T. G. Bonney, ' Geol. Mag.,' 1889, p. 483, and 1890, p. 536. 



