508 THE DIOEITIC PICRITE OF WHITE HA.TJSE AN^D GREAT COCKTJP. 



37. The DioEiTic Picrite of White Hause and Great Cockup. 

 By J. Postlethwaite, Esq., F.G.S. (Read June 22nd, 1892.) 



This rock is exposed on both sides of Hause Gill, which separates 

 White Hause from Great Cockup; the exposure on the former 

 measures from 12 to 15 yards square, that on the latter mountain 

 being somewhat smaller. The two masses are about 5 mile apart, 

 and are doubtless connected beneath the till which forms the floor 

 of the little valley, the only visible connecting-link being a group of 

 blocks jutting out on the northern bank of the stream, which may 

 or may not be in place. The area here indicated is shown in J. 

 Clifton Ward's 6-inch ' Geological Map of the Lake District ' (now 

 in the Keswick Museum of Local Natural History) and coloured as 

 diorite ; it is also shown as diorite in ' Section I. through Skiddaw,' 

 in Ward's ' Physical History of the English Lake District ;' ^ but, 

 so far as I have been able to ascertain, there is no description of the 

 rock in any of his published works, owing in all probability to the 

 fact that it lies a little to the north of Quarter Sheet 101 S.E., 

 which embraces the area treated of in ' The Geology of the Northern 

 Part of the English Lake District.' The area is shown in the 

 accompanying map, which is based on that of the Ordnance Survey, 

 Sheet 23 (formerly 101 N.E.). 



My first visit to White Hause took place in the spring of 1890, 

 when I was engaged in the preparation of a paper on ' The Deposits 

 of Metallic and other Minerals surrounding the Skiddaw Granite,'^ 

 and I was then struck by the close resemblance existing between 

 the rock at that place and the hornblende-picrite at Little Knott, 

 which lies about 2 miles south-west; indeed, the resemblance is 

 so marked that in the above-mentioned paper I referred to the rock 

 at White Hause as " a large mass of hornblende-picrite of like 

 nature." I re-visited the place in the autumn of 1891, and again 

 in the spring of the present year. I obtained specimens from 

 various parts of the mass, and also from the surrounding rocks, and 

 had slides prepared from some of the specimens. The slides, to- 

 gether with the fragments of rock from which they were taken, 

 were submitted to Prof. Bonney, F.B.S., for examination, and he 

 kindly gave me permission to incorporate his notes in my paper, 

 want of time having prevented him from making them sufficiently 

 elaborate to be printed separately. 



The dioritic picrite is a coarsely crystalline rock of a dark olive- 

 green colour, consisting of several varieties of hornblende, also quartz, 

 felspar, calcite, serpentine, iron peroxide, and probably a little 

 apatite, ilmenite, and viridite. On White Hause the rock is very 

 coarse, some of the crystals being nearly 5 inch in diameter ; the 

 exposure on Great Cockup is somewhat finer, but the mineral con- 



1 Geol. Mag. for 1879, p. 54. 



2 Trans. Oumb. & Westm. Assoc, no. 15 (1889-90), p. 75. 



