334 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1917. 



ogy, we may correlate the extensive sand and gravel terraces and 

 plains of the River Foyle near St. Johnstown at levels of 50 and 

 75 feet with the two higher beaches. The Belfast section, to be de- 

 scribed next, however, leaves no room for such an elevation. 



A far more complete record of the changes from the cold of the 

 glacial period to the warm conditions of the climatic optimum and 

 back to the present climate and level in the Belfast district is given 

 by dock excavations and other sections in the estuarine clays and 

 sands. These have been described by Mr. Lloyd Praeger, in a very 

 elaborate memoir (1892). The best section is that exposed at the 

 Alexandra Dock, Belfast, which is as follows: 



9. Surface clays, 6 feet 6 inches; depth below high-water mark, 4 feet 



6 inches to 11 feet. 

 8. Yellow sand, 2 feet ; depth below high-water mark, 11 feet to 13 feet. 

 7. Upper estuarine clay, G feet ; depth below high-water mark, 13 feet 



to 19 feet. 

 6. Lower estuarine clay, 6 feet; depth below high-water mark, 19 feet 



to 25 feet. 

 5. Gray sand, 2 feet ; depth below high-water mark, 25 feet to 27 feet. 

 4. Peat, 1 foot 6 inches; depth below high-water mark, 27 feet to 28 



feet 6 inches. 

 3. Gray sand, 2 feet ; depth below high-water mark, 28 feet 6 inches to 



30 feet 6 inches. 

 2. Red sand, 4 feet; depth below high-water mark, 30 feet 6 inches to 



34 feet 6 inches. 

 1. Reassorted bowlder clay, base not reached, 15 feet; depth below high- 

 water mark, 34 feet 6 inches to 50 feet. 



The same series though less complete is met with at many points 

 along the coasts of Counties Down, Antrim, and Derry. In drawing 

 conclusions from it we must use the principles set out in the introduc- 

 tion showing the relations of the color of deposits to the conditions 

 under which they were formed. The sands 2, 3, and 5 are evidently 

 marine, derived from the underlying bowlder clay ; the gray color of 

 Nos. 3 and 5 would lead us to infer that they were formed under 

 colder conditions than No. 2 ; these cold conditions are confirmed by 

 a study of their fossils. At Belfast and most other localities these 

 are limited to a few starved Foraminifera, but from the gray sand 

 underlying the estuarine beds at Larne were obtained a number of 

 fine examples of the northern shell Crenella decussata, which still sur- 

 vives, though rare, in Larne Lough. The same species occurs, but 

 very rarely, in gray sand beneath the estuarine clays at Maghera- 

 morne. A gray, sandy silt, with Saliss Jierhacea and Lepidurus 

 (Apus) gladalis, which occurs in the same relative position in the 

 Isle of Man, is probably on the same horizon, whose most westerly 

 known occurrence is probably the 20 feet of a very fine, grayish sand, 

 without fossils, below stratified gravels in a section in the Faughan 



