I. GEOLOGY. 825 



B. Welsh Volcanic Rocks. 



9. Felstone, a metamorphosed ash, Rigghause End, Vale of St. John, 



Cumberland. (Polarized light.) 



10. Felstone, Aran Mowddwy. Also represents the structure of Fig. 9. 

 when viewed with plain light. 



11. Felstone, Aran Mowddwy. (Polarized light.) 



12. Felstone, Aran Benlynn. 



13. Felstone, Llanberis Route, Snpwdon. 



14. Slaggy felstone or altered streaky ash, Llanberis Route, Snowdon. 

 NOTE. The Welsh felstone probably represents the modern trachytes or 



quartz-trachytes, and the Cumberland lavas the modern trachy-dolerites and 

 basalts. 



3253f. Three Plates of small water-colour drawings, 

 1J inches in diameter, made direct from the microscope by the 

 contributor, illustrating Microscopic Rock-structure. 



J. Clifton Ward. 



A. Modern Volcanic Rocks. 



1. Trachyte, Solfatara, x 40. 



2. (Polarized light), x 15. 



3. Leucitic lava of 1631, Vesuvius, x 15. 



4. Alban Mount, Rome, x 14. 



" }> >i 



(Polarized light). 



6. Lava of 1794, Vesuvius, x 6. 



7. x 45. 



Ancient Cumberland Volcanic Rock. 



8. Lava, Eycott Hill, x 25. 



9. Brown Knotts, Keswick, x 30. 



10. near Wastwater. (Polarized light), x 15. 



11. Felsite, amid altered ash, Bleaberry Fell, Keswick, x 60. 



12. Ash, Steel Fell. (Polarized light), x 15. 



13. Altered streaky ash, Base Brown, x 15. 



14. Altered ash, Hart Side, x 20. 



B. Illustrating the Metamorphism of Volcanic Rocks around the Granites of 

 Eskdale and Shap. 



1. Altered ash, Yewbarrow, x 50. 



2. Altered contemporaneous trap (?) close to granite, x 50. 



3. Same field of view, in polarized light, x 50. 



4. Highly altered ash, close to granite. (Polarized light), x 50. [ 



5. Bastard granite. (Polarized light), x 50. 



6. True granite, x 50. 



7. Junction of highly altered ash with Shap granite. (Polarized light), 



x 25. 



C. 



1. Altered Skiddaw slate passing into quartz felsite, Clough Head, St. 



John's Vale, x 30. 



2. Quartz felsite, St. John's Vale, x 30. 



3. Altered Skiddaw slate, Red Pike, x 70. 



4. Buttermere, x 70. 



