576 DR. J. W. EVANS ON MECHANICAILY-FORMED [Aug. I9OO5. 



hills of the same composition and origin are also commonly found*, 

 on coral-islands : see [28] pp. 154-56. l 



On the shores of the Sinaitic peninsula, near the northern end of 

 the Gulf of Suez, oolitic deposits maybe seen in course of formation. 

 The oolite-grains are thrown up on the beach by the waves, and are 

 gathered by the wind into long dunes parallel to the sea-shore. 

 Thence they are blown inland by the westerly sea-breezes, and at 

 Wadi Deheese, 2| miles from the sea, Prof. Walther found a sandy 

 deposit composed partly of oolitic grains, partly of desert-sands, and 

 it extends still farther inland [29] : see also [19, 25, & 30]. 



Louis Agassiz [18] has described the formation of oolitic sand- 

 dunes by wind-action in Salt Key between Florida and Cuba. In- 

 Double-headed Shot Key these dunes have been consolidated into 

 a hard rock that rings under the hammer. It is ' pretty regularly 

 stratified, but here and there like torrential deposits' (op. cit. p. 373), 

 evidently a kind of false-bedding. Orange Key contains the same- 

 rock. 



VIII. Colder Eegioxs: the Foraminiferal Deposits of Dog's 

 Bat (Galwav). 



Outside the tropics such deposits as those which we have been con- 

 sidering are, at the present time, of much less importance. Coral- 

 islands, with which they are so often associated, are no longer found. 

 The colder water can dissolve more carbonic anhydride, and therefore 

 more carbonate of lime, without being saturated, and is less liable 

 to concentration by evaporation. Fine-grained calcareous material 

 carried along by moving water will soon be dissolved, and false- 

 bedded limestones will rarely, if ever, be formed under water. 

 Littoral and aeolian deposits are, however, occasionally met with. 



I am informed by Mr. R. Welch, of Belfast, that the isthmus of 

 Earawalla, between Dog's Bay and Gorteen Bay on the south- 

 western coast of Galway, consists of low dunes which are largely 

 calcareous and contain much foraminiferal material. At some 

 points on the Dog's Bay side subfossil land-shells are found 

 embedded in a loamy matrix containing remains of foraminifera. 

 Where sections are available, they do not show the lines of stratifi- 

 cation as clearly as in the arenaceous ajolian deposits in the North 

 and East of Ireland, but there are brown bands here and there 

 corresponding to former hollows where vegetable matter seems to 

 have collected. Very few, if any, marine shells occur except such 

 as appear to have been derived from kitchen-middens in the vicinity, 

 or may have been carried up by birds for food. The isthmus is 

 about 1000 yards long from north-east to south-west, and about 

 ;$50 yards in width between the two bays. 



Similar deposits are still in process of formation on the isthmus. 



1 [Lantern-slides of calcareous seolian deposits, prepared from photographs 

 taken by Dr. C. W. Andrews in the Cocos-Keeling Archipelago, were exhibited 

 at the meeting at which this paper was read.] 



