1883-1884.] 229 



diameter is less than usual. The present entrance is by a ragged 

 hole on the south-west side, but there are indications of a built- 

 up opening on the east side, about six feet above the ground, 

 with sloping jambs and a flat stone lintel, which was most likely 

 the original door. This was very small, being only eighteen 

 inches wide and five feet six inches high. This tower, like the 

 one at Drumbo, appears to be of the earliest type, the arch 

 having been nowhere used in its construction, nor are there any 

 traces of ornament to be seen. The tower is built of the basaltic 

 boulders which still thickly strew the beach of the island, and 

 which present to the geologist several interesting problems. 



That the high central bank of boulders and clay, with its noble 

 crown of ancient trees — the subangular and ice-worn blocks, 

 nearly all of them basalt, which line the more exposed western 

 shore, the smaller fragments of representatives from every 

 northern county, granites grey and red, porphyry, gneiss, 

 micaschist, sandstone, and slate, which cover the eastern side 

 of the long flat spit which forms half the island, and the bed of 

 tenacious clay which underlies them all, and stretches also 

 north and south along the beach of the mainland — that all 

 these are alike relics of the " great ice age" may be taken for 

 granted ; but the precise position to be assigned them in the 

 history of the glacial epoch is not yet clearly defined, and still 

 offers a task which seems specially the province of the members 

 of the Naturalists' Field Club. 



Does the clay, for instance, pass right under the island, or is 

 there a central basaltic boss round which it lies, and against 

 which it rests ? Again, how comes it that the blocks of basalt 

 are mostly seen along the western side of the island, and the 

 miscellaneous collection of smaller stones along the eastern } 



It is clearly established also that the nodules of ironstone 

 which contain the plant remains exist in situ in the clay bed 

 both on the island and the mainland ; and the lignite and fossil 

 wood, once so plentiful on the beach, was doubtless washed out 

 of the same deposit. Where is the parent bed from which they 

 were originally brought to be deposited in this clay ? Can any 



Q 



