32 



and stated in abstract in Nature of 23rd June, 1870. The 

 writer of the present paper has endeavoured to show that the 

 same theory will account for the distribution of cyclones 

 wherever they are formed. 



Mr. Robt. Young, C.E., on the same evening read papers on 

 "The Boulder Clay of the Belfast District," and "The Great 

 Fault in Carrickfergus Commons." He stated his reason 

 for now bringing the first subject prominently before the 

 society — that in a former communication, in which the suc- 

 cessive elevations of the land had been discussed, the variety 

 and extent of the topics had not permitted his doing more 

 than giving a brief glance at this important formation, which 

 in other quarters is occupying the attention of distinguished 

 geologists, and that since that time he had been able to explain 

 some of the formerly obscure and intricate questions associ- 

 ated with the subject, in respect of the origin, distribution, 

 and age of the beds. As regards the position or geo- 

 logical age of the boulder clay, it may be said to form a 

 coating of unequal thickness over a great portion of the de- 

 nuded surface of the entire rock series of the Counties of An- 

 trim and Down, from the granite and gneiss series on the one 

 hand, to the traps on the other, and resting indifferently and 

 unconformably on the Silurians, Carboniferous, Permian, 

 Triassic, Liassic, and Cretaceous. Speaking in general terms, 

 it is a mass of unstratified tenacious clay, containing immense 

 quantities of rounded and frequently polished, grooved, and 

 striated boulders, also angular blocks more or less polished 

 and striated, both of these not only of the local rocks, such as 

 the Silurian slates, sandstones, chalk, and trap beds would 

 furnish, but also of syenites, porphyry, rose-quartz, mica slate, 

 jasper, and granite, differing from any in these counties and 

 indicating a north-westerly origin. In size these vary from 

 a hand pebble to masses weighing twenty tons and upwards, 

 and the striation in the boulders is always in the line of the 

 longer axes. Where the underlying rock is to slate, trap or 



