380 
TATE: YORKSHIRE PETROLOGY. 
ExPLAi^ATION OF PlATES. 
All the figures were drawn with camera liicida, by transmitted 
light, unless otherwise stated. 
Plate 18 a 
Fig. 1. Mica-syenite. About 100 yards below the last slate 
quarry, Dale Beck, Ingleton. x 50. 
Fig. 2. Mica-syenite. 350 yards below Pecca Steps, Thornton 
Beck, Ingleton. x 50. 
Plate 19. 
Fig. 3. Hornblende. Sections in outline, by reflected light. 
X 25. 
Fig. 4. Orthoclase felspar. Crystal altered along cleavage 
lines. X 240. 
Fig. 5. Do. Microfelsitic structure, under crossed 
Nicols. X 240. 
Fig. 6. Biotite mica. Microliths arranged in three direc- 
tions. X 350. 
Fig. 7. Do. Ferriferous products following cleavage 
planes. x 130. 
Fig. 8 to 11. Do. Ferriferous products symetrically 
arranged in relation to the basal plane, x 10 x 60 x 130 x 250. 
Fig. 12. Biotite mica. Bent plates, and skeletal crystals of 
mag-netite. x 25. 
Fig. 13. Do. Bent and frayed-out plates more highly 
magnified. x 130. 
Fig. 14. Magnetite. Skeletal crystals. x 25. 
Plate 20. 
Fig. 15. Felspar cluster enclosed by biotite. x 25. 
Fig. 16. Fictitious pseudomorplis after olivine. x 60. 
Fig. 17. Do. do. X 20. 
Fig. 18. Do. after zoned nepheline. x 60. 
Fig. 19. Do. do. X 60. 
Fig. 20. Calcareous shales, altered by contact. x 10. 
Fig. 21. Biotite plate passing to the zoned nepheline 
stage. X 60. 
Fig. 22. Do. do. Olivine stage, x 25. 
Fig. 23. Calcite infilling cavity, lined by biotite. x 25. 
