174 Notices of Memoirs — Mineralogy. 



vicinity of Cahir, co. Tipperary, may possibly be other representatives 

 of this drift. In the first locality it lies under a drift which seems to 

 be due to a glacier that came down one of the valleys of Slieve 

 Aughta, and probably was entombed during a severe season, when 

 the glacier exceeded its normal length, thereby burying a lacustrine 

 accumulation under Moraine drift. In the second case the inter- 

 bedded peat occurs on very high ground, and is undoubtedly in part 

 covered by Moraine drift ; but whether the whole of the 96 feet over 

 it is of that nature, I cannot say, as the pits were closed long before 

 the country was visited.^ Of the third locality only a very scanty 

 record is given, and from it the forty feet over the peat might be 

 either Boulder-clay or Moraine drift ;^ there is, however, on that 

 country a considerable quantity of Moraine drift that has been sup- 

 plied by the ancient glaciers from the neighbouring hills. 



Since the above was sent to press I learn from Prof. J. McE. Hughes, 

 of Cambridge, that he believes "the whole of the beds containing the 

 recent temperate shells in North Wales and to the north and east of 

 St. Asaph are merely the result of a Post-Glacial sea eating back 

 cliffs of Boulder-clay." " It is known that there have been great 

 changes of level since the great cold, and whenever the sea washed 

 the base of a Boulder-clay cliff, it must, as now, have undermined 

 it, and mixed up re-sorted Boulder-clay and shells of the later period, 

 while here and there great slips would throw old beaches on end 

 and bury lai-ge masses of clay in sand and shingle." I also find that 

 Professor Hughes has stated this a short time since at a meeting of 

 the Geological Society of London.^ 



MINERALOGY. 



I. — Corundum; its Alterations anb Associateb Minerals. By 

 F. A. Genth. Contributions from the Laboratory of the 

 University of Pennsylvania, No. 1. Pp. 46. 



THIS memoir relates mainly to the occurrence of Corundum in 

 North America. The largest deposits occur in the chromiferous 

 serpentine, or chrysolite formation, and in the adjacent rocks, 

 although the mineral is also found in small quantity in rocks of 

 Laurentian age, and in certain slates referred to Dr. Emmons' 

 Taconic system. Dr. Genth thinks it not improbable that the emery 

 beds in Asia Minor and in Greece may correspond in age with the 

 corundum and emeiy of the chromiferous region in the States. 



The author describes a large number of minerals which occur 

 in association with the American corundum, and are supposed to 

 result in some cases from its alteration. Among these substances 

 are four new minerals, described under the names of Dudleyite, 

 Kerrite, Maconite, and Willcoxite. 



1 Geol. Mag. Oct. 1865, and Mem. Geo!. Survey, Ireland, Ex. Sheet 137, p. 50. 



2 Paper by T. Oldham, M.R.l.A., Journ. Geol. Soc. Dublin, vol. iii. p. 195. 



3 Geol. Mag. Jan. 1874. 



