460 W. M. Hutchings — Coniston Flags at Shap.. 



For certain reasons I have taken much interest in the altered flags 

 of Wasdale Beck, and have this summer paid another visit and 

 collected a large number of fresh specimens, from which I have had 

 sections prepared. 



It may be worth while to note one or two of the results of the 

 study of these and former sections, though all the main points as 

 regards these rocks have been so completely dealt with in the 

 above-mentioned paper. 



There are two contact-minerals to record not previously observed 

 here by Harker and Marr, nor by myself, viz. hornblende and garnet. 

 The former occurs in large quantity in two of my sections several 

 hundred yards above the falls near the hotel, but before the develop- 

 ment of any of the " spots " in the altered flags. It is a very 

 pale-green variety ; so pale that in very thin sections its colour 

 and dichroism are barely perceptible. I suppose that, though not 

 quite colourless, it may be reckoned as tremolite, to which variety 

 the hornblende of contact-slates, etc., is usually referred. The 

 extinction-angles are mostly 16° to 18°, but sometimes higher. It 

 occurs as good-sized irregular grains, long prismatic bits with 

 ragged ends, and small fragments disseminated through the rock. 

 The amount of brown mica present is very much diminished in the 

 sections which contain hornblende. 



My specimens are not sufficiently frequent to determine the points 

 of appearance and disappearance of the hornblende along the course 

 of the stream ; but at one point a section very full of it was taken 

 a few feet away, later-ally, from another section which does not 

 contain a trace of the mineral. 



Harker and Marr point out that, as the strike of these beds 

 coincides very closely with the line of exposure along the stream, 

 we need not expect any variation in the original nature of the rocks. 

 But they must have varied a good deal within narrow limits across 

 the strike. These hornblendic specimens are different in several 

 ways from the more normal rock, notably in the amount and size of 

 the quartz present. Doubtless, also, they were originally calcareous 

 bands, while most of the flags exposed in the beck were not. 



Somewhat higher up the stream, and at about the same stage as 

 the development of decided " spots," the garnet appears in great 

 force. It is quite colourless and quite isotropic, with large amounts 

 of included granular and microlithic material not determinable. 

 The garnets are mostly in the form of crystals, but also as rounded 

 and irregular grains. The largest have a diameter of -^^-^ inch. 

 They are mostly pretty evenly dispersed and occur indifi"erently in 

 the spots and in the surrounding mosaic, but at some parts of the 

 slides they are aggregated into large clusters and packs. 



This mineral, again, seems to be very local in its occurrence, 

 appearing and disappearing within a distance of a few yards along 

 the slide, and of a few feet across it. 



One of my objects in taking a new series of specimens was to 

 endeavour, if possible, to obtain more evidence as to what is the 

 real nature of the substance, or substances, in course of formation in 



