[ 174 J 



XII. 



THE GLACIAL GEOLOGY 0¥ THE NOETH-WEST OF IRELAND. 



By J. KAYE CHAELESWORTH, D.Sc, Ph.D., M.E.T.A., F.G.S., 

 Professor of Geology, Queen's University, Belfast. 



" ' (Plates VIII -IX.) 



[ReadjANUAUv 14. Published SEi-TiiMiiEK 26, 1924.] 



Contents. 



PAGE 



Introduction, .... 174 



BiBLIOGltAl'HY AND CUUUENT ThEOUY, 1(5 



Geological Stuuctuke and Physical 

 Features, . . . .180 



Signs of Glaciation and General 

 Character of the Drift Deposits, 182 

 V. — Earlier Sco'itish Glaciation, . 187 

 VI. — Donegal Glaciation during its 

 Maximum Phase, 



I. 



II. 

 III. 



IV. 



1. Country along the Ice-shed, 



2. Drumlin Belt around Donegal 



Buy, . . • . 



3. Glengesh Plateau, 



4. Deriyveagh and Glendowan 



Mountains, 



5. Errigal-Muckish Ridge, 



0. Kosses and Bloody Foreland, 

 7. Northern Peninsulas, 

 S. Valleys of the Finn and Foyle 

 9. Inishovven, . 



10. Si)eirin Mountains, 



11. Barnesmore Granite Boulder 



Dispersal, 



12. South-eastern Area, 



196 

 199 



199 

 203 



207 

 209 

 210 

 214 

 210 

 216 

 217 



219 

 230 



VII. — Retreat of thu Donegal Ice, . 



1. Spurrin Mountains, 



{a) First Stage, 

 (4) Second Stage, 



(c) Third Stage, 



[d] Fourth Stage, 

 {e) Fifth Stage, 



2. Tyrone Glacier, 



3. Slieve Beagli and the Clogher 



Valley, . . . . 



4. Fintona Hills, 



5. Fintona and Erne Glaciers, . 



6. Foyle and Swilly Glaciers, . 



7. Mulroy, Sheephaven and 



Glenna Glaciers, 

 S. Rosses, Dunlewy and Gwee- 



barra Glaciers, 

 9. Glengesh Plateau and country 



nortli of Donegal Bay, 



10. Great Finn Glacier, 



11. Barnesmore Hills, 



VIII. Re- ADVANCE OP THE SCOTTISH IcE, 



IX. — Stream Diversions, . 

 X. — Some General Considerations, 

 XI. — Summary of Conclusions, 



PAGI! 



235 

 237 

 238 

 242 

 24o 

 250 

 257 

 260 



266 

 272 

 275 

 278 



281 



284 



286 

 288 

 293 

 294 

 299 

 304 

 310 



I. — Introduction. 

 In the present paper it is proposed to describe the results of an investigation 

 of the glacial plienoinena exhibited in the extensive region lying to the west 

 of the longitude of Cook.stov?n,^ and to the north of the latitude of Clones, 



' The area to the east has been fully described by Dr. A. R. Dwerryhouse, (The 

 Glaciation of North-Eastern Ireland. Quart. Journ. Geol. Soc, Isxix (1923), 

 pp. 352-422.) 



