xiv LIST OF ILLUSTRATIONS. 
Page 
Section . . Near Llandeilo, from the Lower Silurian to the edge of the great 
South-Welsh Coal-field • 55 
Section . . Near Llangadock, from the Lower Silurian to the Old Eed Sandstone 56 
Sketch . . Llanwrtyd Wells 57 
Sketch . . View from the Slaty Lower Silurian Eocks near Llanwrtyd, Brecon, 
overlooking rounded Hills of Upper Silurian, with Mountains of 
Old Eed Sandstone in the distance 58 
Sections . . Unconformable Eelations of Llandeilo Flags and Upper Silurian, 
near Builth 59 
Section . . Llandeilo and Caradoc Eocks, East flank of Berwyns 60 
Fossils (12). Lower Silurian Graptolites 61 
Sketch . . The Caradoc Eange 64 
Section . . Eelations of Caradoc Sandstone to the Upper Silurian Eocks in 
Shropshire 64 
Sketch . . View from the East side of Caer Caradoc 65 
Section . . Eelations of the Caradoc Formation, Shropshire 66 
Fossils (13). Caradoc Fossils 68 
Fossils (14). Caradoc Trilobites 69 
Section . . Eelations of the Llandeilo and Caradoc Eocks, South Wales ... 73 
Sketch . . Whittery Quarries in Marrington Dingle .— 77 
Section . . Alternations of Volcanic Ash and Schist 77 
Section . . Ideal Eepresentation of the manner in which Submarine Volcanic 
Dejections probably were formed during the Lower Silurian Period 78 
Section . . Alternations of Llandeilo Flags and Schists with Volcanic Grits, 
on the North-western face of Gelli Hill 78 
Sketch . . View of the Breidden Hills near Welsh Pool, from Powis Castle . 80 
Section . . Across the Breidden Hills 80 
Section . . Across the Gelli Hills 81 
Section . . Llandeilo Schists and Trap-rock at Tin-y- Coed 81 
Section . . Geological Structure of Cader Idris 83 
Section . . Across the Snowdon Eange ^ . . . . 84 
Section . . Noeth Griig . , 87 
Section . . Eelations of the Upper Llandovery Eocks to the Deposits above 
and below, between the Longmynd on the N.W. and the foot of 
Wenlock Edge on the S.E <. . . 89 
Fossils (15). Upper Llandovery Fossils . 90 
Section . . Conglomerate on the South Flank of the Longmynd, with copper- 
veins 91 
Sketch . . View of the Malvern Hills from the West 92 
Section . . From the Malvern Hills to Ledbury 95 
Fossils (16). Fucoid in Malvern Sandstone 96 
Section . . Caradoc or Bala Formation supporting the Tarannon Shales and 
Denbigh Grits (E. of Bala) . . 102 
Section . . Borders of Eadnor and Montgomery 102 
Section . . Eadnorshire, S. of Llanbister 103 
Section . . General Order of the Upper Silurian Eocks included between the 
Upper Llandovery or May Hill Sandstone and the Old Eed 
Sandstone 106 
Section . . Lower Wenlock at Corton, near Presteign 107 
Section . . Altered Limestone of Nash Scar 107 
Section . . Of Silurian Eocks around Hanter Hill 108 
Sketch . • . View from Stanner Eocks (Worsel Wood, Hanter Hill, and Hergest 
Eidge in the distance) 109 
Section . . Across the Elevated Valley of Woolhope 110 
Fossils (17). Trilobites of Lower Wenlock or Woolhope Limestone Ill 
Sketch . . Wenlock Edge, as seen from the Hills of overlying Ludlow Eock on 
theS.W 115 
