TERTIARY VOLCANIC ACTION 253

APPENDIX I—Mineral Resources 265

APPENDIX II—Palæontology of the Cretaceous Deposits 273

INDEX OF AUTHORS 287

GENERAL INDEX 289

LIST OF ILLUSTRATIONS

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PLATE I.— FIG. 1. On the Niger above Igbo 12

FIG. 2. Lokoja and Mt. Patti 12

PLATE II.— The Confluence of the Niger and the Benue 20

PLATE III.— FIG. 1. Abuja Rock 28

FIG. 2. Abuja Rock from the Walls of Abuja 28

PLATE IV.— FIG. 1. A Granite Mount near Abuja 48

FIG. 2. The Margin of the Nassarawa Tableland from Jaginde 48

PLATE V.— FIG. 1. Worn Volcanic Cones near Awe 60

FIG. 2. The Wase Rock 60

PLATE VI.— FIG. 1. Yendam Hill, Yola Province 76

FIG. 2. Craters at Mboi 76

PLATE VII.— FIG. 1. Craters in the Mboi Hills 90

FIG. 2. A Crater in the Mboi Hills 90

PLATE VIII.— FIG. 1. Exfoliation in the Kilba Hills 104

FIG. 2. The Gorge of the Kaduna at Zungeru 104

PLATE IX.— FIG. 1. On the Summit of the Bauchi Plateau; the Parade Ground at Bukuru 120

FIG. 2. On the Plateau looking Westward from Bukuru 120

PLATE X.— FIG. 1. A Worn Volcanic Hill on the Bauchi Plateau near Zamagan 134

FIG. 2. The Twin Cones of Kereng from Panyam 134

PLATE XI.— FIG. 1. Hillocks of Drift on the Bauchi Plateau near Vom 152

FIG. 2. Hillocks of Drift to the West of Naraguta 152

PLATE XII.— FIG. 1. A Granite Mount near Bauchi 170

FIG. 2. „ „ „ 170

PLATE XIII.— FIG. 1. The Sandstone Hills of Ture 190

FIG. 2. Ture or Tangale Peak 190

PLATE XIV.— FIG. 1. Dozi Hill, Kerri-Kerri 210

FIG. 2. A Trench-like Valley near Lele in Kerri-Kerri 210

PLATE XV.— FIG. 1. Cretaceous Sandstones and Shales at Awe 224

FIG. 2. A Flat-topped Hillock of Drift above Naraguta 224

PLATE XVI.— Upper Benue Sandstones and Conglomerates upon a Hummocky Granitic Floor 245

PLATE XVII.— FIG. 1. Inselberge Landscape around } Abuja } } _Frontispiece._ FIG. 2. Inselberge Landscape in } Northern Yola }

PLATE XVIII.— FIG. 1. The Salt Fields of Awe; Volcanic Hills in the Background 260

FIG. 2. Akiri Saltings 260

PLATE XIX.— Cretaceous Mollusca 286

PLATE XX.— „ „ 286

PLATE XXI.— „ „ 286

PLATE XXII.— „ „ 286

PLATE XXIII.— „ „ 286

PLATE XXIV.— „ „ 286

MAPS—

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I.—PRIMARY WATERSHEDS AND RIVER SYSTEMS 4

II.—THE BAUCHI PLATEAU AND THE NASSARAWA TABLELAND 40

III.—AXES OF ELEVATION 236

IV.—MINERAL RESOURCES 266

V.—COLOURED GEOLOGICAL AND TOPOGRAPHICAL MAP AND SECTIONS _At end of Volume_

THE GEOLOGY AND GEOGRAPHY OF NORTHERN NIGERIA

NORTHERN NIGERIA