100 MR. E. E.WALKER ON THE GARNET- BEARING [Feb. 1904, 



continued northward towards Laythwaite Sike, and southward to 

 Castle Crag and on to Randale Beck. 



Between Whelter Knotts and Laythwaite Sike an interesting 

 group of rocks occurs. The ground is much faulted, diabase- 

 dykes coming in along the faults. All along the road near the 

 School and Rowan Park a yellow rhyolific ash with 

 pyrites is developed. An analysis of a specimen from Rowan 

 Park yielded a silica-percentage of 72* 18. 



In Laythwaite Sike a very dark-brown rock occurs, either alone, 

 or in lenticular fragments in a yellow matrix : this gave a silica- 

 percentage of 31*77. Microscopical examination shows the rock to 

 be made up almost wholly of chlorite, and the low silica-percentage 

 obtained supports this conclusion. Along the 1500-feet contour 

 from Laythwaite Sike to Whelter Knotts this mixed yellow-and- 

 black rock becomes converted into a schist with white quartz and 

 a greenish mineral. Weathering of the rock produces a wonderful 

 mosaic, the quartz standing out from the red iron-oxide produced 

 by the decay of the green constituent. This mineral, under the 

 microscope (3806)-, is seen to occur in irregular yellowish patches, 

 giving high polarization-tints. It is derived from chlorite, for 

 a section (3812) shows the passage of one into the other. At 

 the margins of these patches, and scattered throughout the matrix 

 of quartz-grains, occur minute irregular prisms of a greenish, 

 strongly-pleochroic mineral, giving high polarization-tints and exi 

 tinction oblique to the length of the prisms. Wisps and tufts of 

 the same mineral have been noticed very frequently in association 

 with chlorite in the ' streaky' rocks elsewhere. It must be closely 

 allied to chlorite in composition. A compact quartz-schist has 

 been produced by dynamic metamorphism from the yellow and 

 brownish aggregate. The silica-percentage is intermediate between 

 the two given above, for it is found to be 64- 7 7. 



On the east side of Haweswater ■ streaky' rocks are well developed. 

 They occur in the north between High-Laithes Pike and Walla Crag, 

 being continued from Pinnacle Howe on the opposite shore. Cleaved 

 Eycott Lavas form a thin band near the base of the series. They 

 run in a narrow belt, frequently interrupted b} r diabase-intrusions, 

 to the head of Naddle Beck, and then spread out over the heather- 

 covered ground as far as Woof Crag and Powley's Hill, descending 

 to the lake along the line of Guerness Gill. Patches of intrusive 

 quartz-porphyry are often found, and a considerable mass of the same 

 rock is found in them on Mardale Banks, south-east of the end of 

 the delta. 



At Woof Crag a garnetiferous andesite (already mentioned 

 on p. 97) occurs, overlain by banded ash. Along the junction 

 movement has taken place, with the result that the lava shows 

 excellent crush-conglomerates. Basic dykes break through it 

 frequently. Diabase- dykes of a dark-green colour and of tine 

 grain are common on the west side of the lake, occurring south of 

 Birk's Crag and above the Schools. Quartz-porphyry dykes 

 are also found on Whelter Knotts. 



The intercalation of lava and ashes which do not contain garnets 



