GEOLOGICAL SOCIETY 01 DUBLIN. 95 



2. A new kind of Trilobite, by him named Palceopyge Ramsay i. This 

 appears tolerably well defined, and is the most interesting Cambrian 

 fossil yet discovered. He also found marks strongly resembling rain- 

 drops and ripple-marks, which point out to littoral action and exposure 

 to the atmosphere. These discoveries form a new era in the history of 

 the Cambrian formation. 



There is also another subject which has been treated with his usual 

 ability by our Secretary, Mr. Haughton; and, although the detailed 

 results have been communicated directly to the London Society, they 

 are so important, and the manner in which he has conducted this latterly 

 much neglected branch of inquiry, Mineralogical Geology, reflects so 

 much credit on our Society, that I am sure you will be glad to hear 

 some of the conclusions to which his analysis leads. The title of his 

 paper is — " A Detailed Analysis of the Granites of the S.E. and K.E. of 

 Ireland." Prom this it appears that — 



1. In the S.E. of Ireland the granites may be classified by the pre- 

 ponderance of potash over soda, and vice versa. 



2. The granites of the main chain and of Carnsore are potash gra- 

 nites. 



3. The granites of the intermediate groups are soda granites, and 

 reducible to two types — 



a. The Croghan Kinshela granite. 



b. The soda granite proper. 



4. The potash and soda granites differ from each other in a regular 

 manner in respect to the other constituents, as well as in respect to the 

 alkalies, — the most striking difference being the deficiency of silica in 

 the soda granites, this deficiency being made up by the addition of per- 

 oxide of iron and lime ; and the increase of the specific gravity of the 

 soda granites. 



The granites of the N.E. consist of the granites of the Mourne, Car- 

 lingford, and JSewry districts. 



1. The Mourne granite, on being analyzed, shows a striking resem- 

 blance to the potash granite of Leinster, except in containing 3 per 

 cent, more quartz. This excess of silica is accompanied by a falling off 

 of the lime and magnesia. 



2. The granites of the Carlingford district are of two varieties, both 

 containing a preponderance of potash. The first variety is very like 

 in composition to that of the main chain of Leinster. The second is 

 quite different, both physically and mineralogically. It contains anor- 

 thite and hornblende, but no mica. Indeed, it may be called a kind of 

 syenite. 



3. Newry granite. There are in this vicinity two kinds of granite. 

 Taking a line nearly KS. through Newry from Goragh "Wood through 

 Wellington Inn on the south to Jonesborough, soda granite is found to 

 the north of Newry, and potash granite to the south. 



I may add that, with reference to the age of these rocks, the reviewer 

 of Ansted's " Elementary Geology" (" Natural History Review," 1857, 

 p. 26) classifies the Irish granites as follows : — 



