September, igc6.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



543 



Volcanic Carbon Dioxide. 



The liberation of carbon dioxide from numerous vents is 

 apparently the final manifestation of volcanic activity in 

 the district of Auvergne. All the mineral springs in the 

 neighbourhood are heavily charged with the gas, and one 

 of those at Montpensier, which issues in a large crevice, has 

 long been known as the " poisoned well." Animals that 

 take refuge in the crevice or come to drink the water arc 

 rapidly asphyxiated by the gas, which is always accumu- 

 lating there. The bodies of birds, rabbits, dogs and sheep 

 are frequently found in this crevice, and many children 

 have lost their lives in the same way. Hitherto, this was 

 the only spring of the kind known, but recently it was 

 noticed that the vegetation to the North-East was dis 

 coloured by stains, and these were found to be due to the 

 plants being poisoned by carbon dioxide liberated at these 

 points. Acting on the advice of M. Glangeaud the owner 

 of the land subsequently discovered several places where 

 the gas was being emitted from fissures in the rocks. Two 

 springs were also found in crevices several yards in depth, 

 and these crevices were particularly interesting from the 

 fact that they contained Roman pottery, and the skeletons 

 of oxen, sheep, horses, and a man, and at a lower depth 

 the skeletons of a mammoth and a bison {Bos j>riscus). All 

 of these had apparently been asphyxiated by the gas in the 

 same way as the animals of to-day. Some years ago, it 

 was pointed out that thousands of litres of carbon dioxide 

 were being lost daily in Auvergne, and that it would be 

 profitable to collect and liquefy the gas. This, it was shown, 

 could be done very cheaply and the product would be mucn 

 purer than the ordinary commercial liquid carbon dioxide, 

 which might contain poisonous impurities such as carbonic 

 oxid?, whereas the natural gas contained only carbon 

 dioxide and nitrogen. Liquid carbon dioxide has been 

 prepared for some time past in the volcanic districts of Eifel 

 and Westphalia, and now a start has also been made at 

 Montpensier. The actual amount of gas at present liberated 

 is about 500,000 litres per day, but a much larger quantity 

 conld be collected by means of suitable borings. 



GEOLOGICAL. 



By Edward A. Martin, F.G.S. 



Destruction of Valparaiso by Earthquake. 



Tin; news to hand of an earthquake al \'alpar.ii~o and the 

 surrounding parts of Chili continues the extraordinary earth- 

 quake and volcanic history of this remarkable year. Full 

 details arc not yet to hand, but the country is well known 

 as being liable to such disturbances. The shock reached 

 Professor Milne's instruments in the Isle of Wight soon 

 after midnight of August 16-17, after travelling 6,000 miles, 

 and that authority is reported to have stated that a move- 

 ment of earth was perceptible for more than five hours, the 

 actual time of the greatest shock being 7.15 p.m. on 

 August 16. The city of Valparaiso was concerned in the 

 great earthquake of November 19, 1822, when the shock 

 was felt simultaneously over a space of 1,200 miles of 

 Chilian coast. .At Valparaiso the coast was elevated three 

 feet, a part of the bed of the sea being exposed, the rocks 

 being covered with dead oysters, mussels, and other 

 molluscs. Great fissures showed themselves, this being a 

 phenomenon particularly noticeable in .South .American 

 earlhquakes. Some of the fissures in the granite extended 

 a mile and a half inland from the coast. The whole of the 

 Chilian coast was raised from three to four feet, and sand 

 and mud-cones a few feet high were opened up in nmnerous 

 places. It will be well to nnle wlu-lher similar phrnomcn.i 

 have now been exhibited. 



Chalcedony in the Antrim Basalts. 



The occiu'rence and origin of the Carnmor.ev chakedonv 

 has recently been described by Mr. J.imes Slr.-ich.in. The 

 chalcedony occms in large cracks or veins in the lower 

 basalts of .Antrim. These are sometimes as much as 12 

 inches in width, and from this the cavities thin .awav into a 

 mere h.iir's-breadlh. These veins have apparently been 



formed during the consolidation of the lava, for the vein- 

 sides are coated in all degrees of thickness from a mere film 

 to one inch, with the mineral hullite, which has been de- 

 scribed by Professor Cole as " the altered and hydrated 

 glass of the original basaltic ground-mass." Carnmoney 

 Hill, with its steep escarpment sloping sharply towards the 

 Belfast Lough, is a prominent and picturesque feature in 

 the landscape of the country lying to the north of Belfast. 

 The attention of the geologist is attracted both bv the 

 peculiar shape and the comparatively isolated position of this 

 hill, which represents the site of a'n ancient volcano, from 

 whose throat, in Tertiary times, poured forth part of the 

 Upper Basaltic Lava. On the south side of the hill the 

 denuded "neck" or "plug" of this old volcano may be 

 traced, cutting through the Lower Basalt, the Cretaceous, 

 and older strata. The Upper Basalt and part of the Lower 

 have been removed by denudation, leaving the plugged-up 

 vent, which is almost one-quarter of a mile in diameter. 

 The material of the neck is a vesicular lava similar in ap- 

 pearance to that of the doleritic dykes found in various parts 

 of Co. Antrim. 



When Sea-Erosion Commenced. 



The subject of sea-erosion of our coasts was again dealt 

 with by the British Association at its recent meeting at 

 A'ork, and Mr. Clement Reid, the reader of the paper, is 

 well able to deal with the subject exhaustively. I must 

 confess, however, to a feeling of doubt as to the advisability 

 of attributing the commencement of the erosion of our cliffs 

 to a time so recent as from three to four thousand years 

 ago. I think that such an estimate is liable to misconcep- 

 tion, but I admit that may have been near the time when 

 the sea resumed its position at the foot of the din's. But the 

 cliffs then showing owed their existence to erosion in earlier 

 times,_ although in the meantime, according to the inter- 

 pretation of most modern geologists, the sea had retired, 

 owing to an upheaval of the whole plateau on which the 

 British Isles stand. When the sea again swept down the 

 plain of the North Sea and reached the old ciiiTs which it 

 had in a former age carved out of the land, then, of course, 

 cliff-erosion again commenced, and this mav have been as 

 recent as the time estimated by Mr. Clement Reid. In this 

 way a convenient starting point may be made, so far as 

 modern erosion is concerned. 



The Mediterranean Sea as a Lake. 



The pigmy hippopotamus from Cyprus, whose skeleton 

 has just recently been set up in ' the Natural History 

 Museum, may, with the pigmy elephant of .Malta, be re- 

 garded as the dwarfed representatives of normal races which 

 formerly peopled tracts of land now covered by the 

 Mediterranean Sea. Their existence brings to mind an 

 ancient era when the Mediterranean was a land-locked sea, 

 before the Straits of Gibraltar existed, and when, possibly, 

 the various islands of the sea had a land connection, either 

 with the mainland or an isthmus which connected Italy and 

 Sicily with the African shores. A rise of the sea bottom of 

 about 220 fathoms would cut off the connection with the 

 .Atlantic Ocean, and as a considerable portion of the shore- 

 lino of the Mediterranean would undoubtediv share in such 

 an uprise, the area of the sea would become diminished, the 

 new shores being a series of flat sandy steppes such as are 

 found around the inland lakes of Central .Asia. The loss by 

 evaporation would still be as great as ever, and the Black 

 Sea would be drawn upon to supplv soine of the loss, and 

 would, in consequence, also suffer in area in the course of 

 time, even if its shores did not share in the uprise. The 

 subsidence which brought about the Straits of Gibraltar was 

 apparently, however, not experienced so far east, or the 

 Black Sea waters might have become connected with the 

 Central Asian lakes. It is extremely probable that this con- 

 nection did once exist, and subsequently the level of the 

 Caspi.in has been so altered by the excessive evaporation 

 which takes place upon its surface, that it is now 108 feet 

 below the level of the Black Sea. The sinking down of the 

 stretch of low sandy country which lies between the Sea of 

 Azov and the Caspian to a comparatively slight extent would 

 bring about a connection between their waters, and the 

 Black Sea would pour its waters into the Caspian, and if 

 the movement of subsidence were general, the sea would 

 reach the salt lake of .Aral, and much of Turkestan and 



