XX 
THE ANCIENT VOLCANOES OF GREA T BRITAIN 
KIO. 
PAGE 
31. Diagram illustrating the gradual emergence of buried volcanic cones through the in- 
fluence of jjrolonged denudation . . . . . . .75 
32. Dyke, Vein, and Sill ....... go 
33. Section of Sill or Intrusive Sheet ........ 83 
34. Ideal section of three Laccolites. (After Mr. Gilbert) . . . . .86 
35. Diagram illustrating the stratigraphical relations of the pre-Cambrian and Cambrian 
rocks of the North-west Highlands of Scotland . ..... 112 
36. Map of a portion of the Lewisian gneiss of Ross-shire ..... 118 
37. Section showing the position of sills in the mica-sehist series between Loch Tay and 
Amulree ....... ^^24 
38. Sketch of crushed basic igneous rook among the schists, E. side of Porth-tywyn-mawr, 
E. side of Holyhead Straits ...... ]^28 
39. Section across the Uriconian series of Caer Caradoc . X32 
40. Map of the volcanie district of St. David’s .... 145 
41. Section .showing the interstratifioation of tuff and conglomerate above Lower Mill, 
St. David’s ....... 454 
42. Basic dyke traversing quartz-porphyry and converted into a kind of slate by cleavage. 
West side of Llyn Padarn ••...... 162 
43. Section of well-cleaved tuff, grit and breccia passing up into rudely-cleaved conglomerate 
and well-becldod cleaved fine conglomerate and grit. East side of Llyn Padarn . 163 
44. Section of Clegyr on the north-east side of Llyn Padarn, near the lower end . . 164 
45. Section across the Cambrian formations of the Malvern Hills, showing the position of 
the intercalated igneous rooks. After Phillips . . . . . .170 
46. Section across Rhobell Fawr ....... 178 
47 . Section at the Slate Quarry, Penrhyn Gwyn, north slopes of Cader Idris . . 180 
48. Sketch-section across Cader Idris ........ 182 
49. Section across the Moelvvyn Range ■-..... 185 
50. Section across the anticline of Corndon ....... 190 
51. Structure in finely-amygdaloidal diabase lava, south of mouth of Stinchar River, Ayrshire 193 
52. View of Kuockdolian Hill from the east ....... 194 
53. Section across the Lower Silurian volcanic series in the south of Ayrshire (B. N. Peach) 197 
54. Section of part of the Arenig volcanic group, stream south of Bennane Head, Ayrshire 198 
65. Flow-structure in the lowest felsite on the track from Llanberis to the top of Snowdon . 211 
56. Section of Snowdon ....... 212 
57. Section across the Berwyn Hills. (Reduced from Horizontal Section, Geol. Surv. 
Sheet 35) 219 
58. Section of the strata on the shore at Forth Wen, w'est of Amlwch . . 223 
59. Section of intercalated black shale in the volcanic series at Forth yr hwch, south of 
Carmel Point, Anglesey ........ 224 
60. Green slates overlain with volcanic breccia, Carmel Point ... 224 
61. Blue shale or slate passing into volcanic breccia east of Forth Padrig, near Carmel 
. 225 
62. Section of felsites in the Coniston Limestone group, west of Stockdale . ' . . 232 
63. Fine tuff with coarser bauds near Quayfoot Quarries, Borrowdale . . 234 
64. Diagram of the general relations of the different groups of rock in the Lower Silurian 
volcanic district along the western shore of Lough Mask . . . 253 
65. Veins and nests of sandstone-due to the washing of sand into fissures and cavities of an 
Old Red Sandstone lava. Turnberry Point, Ayrshire .... 283 
66 . Ground-plan of reticulated cracks in the upper surface of an Old Red Sandstone lava 
filled in with sandstone. Red Head, Forfarshire .... 284 
