ASSOCIATED METAMOKPHIC ROCKS OP THE LAKE-DISTRICT. 



597 



to granite are borne out by the results of chemical analysis. The 

 analyses* given below have been made for me by Mr. John Hughes, 

 F.C.S., No. 1 having been already brought forward in a former paper 

 on "Ancient and Modern Volcanic Kocks "f. 



No. 1 is an analysis of the very compact felstone-like rock of 

 Base Brown, figured in the paper just quoted and in the Survey 

 Memoir, and which probably represents an originally fine-grained 

 ash in which metamorphism has developed (as already described) 

 a large amount of chlorite, frequently collected along streaky flowing- 

 lines. 



jSTo. 2 represents the composition of the highly altered coarse ash 

 of Slight Side, within a mile of the nearest granite at the surface, 

 and weathering in a granitoidal fashion. 



Wo. 3 gives the composition of one of the purplish and semi- 

 porphyritic specimens of altered rock, close to the granite. Its 

 microscopic structure is shown in PI. XXXI. figs. 2 and 3, the 

 specimen being taken from the course of Lingmell Beck, near the 

 junction. 



No. 4 is an analysis of the Eskdale granite, taken from a specimen 

 near the edge, south of Great How. 





I. 



Altered ash, 



Base 



Brown. 



II. 



Altered ash, 

 Slight 

 Side. 



III. 



Altered 



Con. Trap, 



Lingmell 



Beck. 



IY. 



Granite, S. 



of Grreat 



How. 



Silica 



69-673 



14-492 



2-296 



•324 



4-554 



3-017 



2-784 



•442 



•4L0 



•343 



•205 



•660 



•800 



68-421 

 15-855 



2-016 



•792 



3-338 



5-627 



2-855 



•172 



' -264 



trace 

 •720 



59-151 



19-212 



5-208 



1-909 



2-933 



4-217 



5-192 



•879 



•360 



•439 



trace 



trace 



•500 



73-573 



13-750 



1-064 



•396 



3-512 



4-315 



2-103 



•615 



' '-6i2 



trace 

 •660 



Alumina 



Lime 



Magnesia 



Potash 



Soda 



Ferrous oxide 



Ferric oxide 



Bisulphide of iron .... 



Phosphoric acid 



Sulphuric acid ........ 



Carbonic acid 



Loss on ignition 





100-000 



100-000 



100-000 



100-000 



2. Remarks on the analyses. — If Nos. 1, 2, and 4 be compared, 

 it will be seen that the analyses come very close to one another, the 

 chief difference between the granite (No. 4) and the other examples 

 being an increase of silica of 4 or 5 per cent in the former case and 

 a slight diminution in the percentages of alumina and lime. When, 



* For the positions of the rocks analyzed, see map, p. 592. 

 f Quart. Journ. Geol. Soc. vol. xxxi. p. 388. 



