ASSOCIATED METAMOEPHIC ROCKS OF THE LAKE-DISTRICT. 589 



9. It can be shown from the geological examination of the Lake- 

 strict that none of the granitoid rocks were probably consolidated at 

 a greater depth than 30,000 feet, while the pressures derived from 

 microscopic examination range from 35,000 to 52,000. 



10. The Skiddaw and Eskdale Granites, formed at a maximum 

 depth of 30,000 and 22,000 feet respectively, both indicate a large 

 surplus of pressure, probably acting outwards and effecting elevation, 

 contortion, and metamorphism. 



11. The Shap Granite, consolidated at a maximum depth of 14,000 

 feet, shows also a large surplus of pressure; and, from its nearness to 

 the surface and its distinct character from the large Eskdale mass 

 probably formed at the same time, it may be taken to represent an 

 immature volcanic vent. It seems likely that this granite was partly 

 formed at a much greater depth than 14,000 feet, but finally consoli- 

 dated at this depth. 



12. Microscopic examination yields nearly the same value for the 

 mean of pressure under which the Lake-district granites were formed 

 as for those of Cornwall. 



13. The quartz-felsite (elvanite) dykes appear to have been formed 

 in this district under a greater pressure than the rocks from which 

 they proceeded; but the circumstances under which consolidation 

 took place in the two cases are not strictly comparable with one 

 another. 



EXPLANATION OF PLATE XXX. 



Examples of Liquid-cavities in the Granitic and Granitoid BocTcs of the Lake- 

 district. 



A. Figs. 1-10. Liquid-cavities in the Shap Granite; of these, figs. 1-5 have 



vacuities not freely moving in the liquid. 



B. 11-20. Liquid cavities in the Eskdale Granite. 



21-28. Liquid-cavities in veins from the Eskdale Granite. 

 29-36. Liquid-cavities in quartz-felsite (elvanite) dykes from the Eskdale 

 Granite. 



C. 37-46. Liquid-cavities in the Skiddaw Granite ; of these, figs. 37-41 have 



vacuities not freely moving in the liquid, and figs. 37 and 38 show 

 crystals of schorl passing through the cavities. 



D. 47-51. Liquid-cavities in the Ennerdale Syenite, or Syenitic Granite. 



E. 52-56. Liquid-cavities in the Quartz Felsite of St. John's Yale ; fig. 55 



shows a vacuity not freely moving in the liquid. 



F. 57-66. Liquid-cavities in the Quartz Felsite dyke of Armboth and Hel- 



vellyn ; in fig- 58 the vacuity moved freely throughout the cavity 

 except into the tubular processes ; in figs. 59, 60, and 63 the vacuities 

 did not move freely in the liquid. 



G. 67-76. Liquid-cavities in the Quartz Felsite of Fairy Crag, Crag Bridge, 



near Shap ; of these, figs. 67, 68, and 71 have vacuities not freely 

 moving in the liquid. 



Note. — All the figures are magnified to the same degree; and the scale is 

 appended to the Plate. Those cavities which contain fixed vacuities are denoted 

 by a small /placed after the number of the figure. 



