SCIENCE-GOSSIP. 



27 



quarries. The entire succession is, however, not 

 perfect, for the highest beds of the " Upper Grey 

 Limestone" have been denuded, and at the Little 

 Orme's Head are altogether absent. Copper lodes 

 on the Great Orme's Head appear to have been 

 worked by the Romans, and again in recent years 

 until abandoned fully thirty years ago. Some of 

 the lodes are faults. It is to the undulation of the 

 Limestone that the ever-varying dip of the beds is 

 attributed. Numerous fossils occur in the " Upper 

 Grey Limestone," and a few are peculiar to the 

 subdivision and the locality, but of these only a 

 single specimen of each has been found. Prodnctus 

 margaritaceus is abundant, though only an occasional 

 species in other localities, and is not found at a 

 lower horizon anywhere else in North Wales. 

 Other species, as Ovthis michetini, formerly supposed 

 to be peculiar to the " Upper Grey Limestone," 

 have been found at the base of the " Middle 

 White Limestone," at the Flagstaff Quarry on 

 the Marine Drive, near the Happy Valley. The 



Jeffreys and by Mr. S. V. Wood, and its contents 

 were afterwards worked out by Messrs. Kendall 

 and Bell. About a hundred species have been 

 obtained thence, mostly mollusca. The deposit 

 stands about 100 feet above ordnance datum, and 

 dips about 5 to north-north-west. In one section 

 it shows yellow sand and clay, blue clay, and fine 

 quartzose sand, of which, however, the blue 

 clay alone is fossiliferous. The evidence of the 

 molluscs seems to show the deposit to be of Middle 

 or Lower Red Crag age. Among characteristic 

 mollusca which occur are Littovina subaperta, Cono- 

 vuhis pyraviidatis, Nassa granulata, Cohimbella sulcata, 

 Nassa reticosa and Turritella incrassata, together 

 with others of a southern character, such as Fusus 

 corneus, Nassa mutabilis, Cardium papillosum and 

 Cardita aculeata. Four species of polyzoans were 

 met with, common to the Coralline Crag and the 

 Italian Pliocenes, fragments of Balanus, and 

 several swimming crabs, detached plates and 

 spines of Echini, three or four species of annelids, 



View of Coal-Pit at Brora, Caithness. 

 (From CadelVs " Geology and Scenery of Sutherland.") 



dolomitization of the Carboniferous Limestone 

 is remarkable, and almost peculiar to that around 

 Llandudno, though it also occurs at Penmon in 

 Anglesey. The "Lower Brown Limestone" has 

 been almost entirely converted into dolomite and 

 portions of the overlying sub-divisions. The filling 

 of the faults has often been changed into dolomite, 

 and the alteration of the limestone is generally in 

 a very capricious manner. In the discussion which 

 followed, Professor Sorby made some interesting 

 remarks on attempts which he had made to 

 artificially produce dolomitization of carbonate of 

 lime. He had, however, only been able to produce 

 pseudomorphs in carbonate of magnesia, but not 

 the two combined as dolomite. 



Pliocene Deposit in Cornwall. — At St. Erth, 

 in Cornwall, is a very interesting deposit, of 

 Pliocene age, in the shape of certain sands and 

 clays which have been exposed on the glebe-land 

 belonging to the vicar of the parish. Attention 

 was called to it some years ago by Dr. Gwyn 



spicules of calcareous sponges, plates of Holo- 

 thurians, and minute stellate calcareous spicules of 

 one of the Tunicata, closely allied to Leptoclinum 

 tenue. From consideration of the fauna, the 

 conclusion has been arrived at by Jukes-Browne 

 and others that the Arctic and the Atlantic Oceans 

 were then disconnected, by reason of an isthmus 

 running across from Europe to America. This 

 connection probably continued from Eocene to 

 early Pliocene times. 



Fossil Ivory. — The quantity of fossil ivory 

 which has been, and is still being, transported frcm 

 Siberia to the markets of the world, seems almost 

 incredible. Middendorf calculated that not less 

 than 110,000 pounds of tusks and teeth are col- 

 lected every year, representing at least 1,000 

 individual mammoths. At this rate, during the 

 last thirty years, the remains of 30,000 mammoths 

 have been used up. By the middle of the 

 eighteenth century the trade commenced to assume 

 considerable proportions, large stores being dis- 



