HA RD WICKE'S SCIENCE- G OSSIP. 



219 



later earth movements. The triassic beds had been 

 faulted and invaded by basaltic dykes in pre- 

 cretaceous time, for upon their denuded edges the 

 cretaceous rocks were laid down. It was along the 

 northern part of this line that the previous earth- 

 quake occurred ; it was near the southern part of 

 this line that the recent earthquake had originated. 

 The area most affected by the recent earthquake was 

 a vast plain of tertiary and cretaceous rocks. The 

 older rocks underlay these unconformably, but at 

 unknown depths. It might, perhaps, be found that 

 the transmission of the shock to distant points had 

 depended in part upon the range on the harder and 

 older rocks beneath, as was very evidently the case 

 with the East Anglian earthquake. In this earth- 

 quake the great structural damage was confined to a 

 small area ; the distant points at which it was felt 

 were, in most cases, upon or near to exposure of the 

 palxozoic rocks, and Birmingham was one of these 

 distant points. In other cases, earthquakes were 

 known to be related to lines of fault. 



The later telegram stated, that Mr. M'Gee had 

 been sent by Major Powell to investigate the effects 

 of the earthquake at Charleston, and that he found 

 the local evidence, such as the direction of the 

 fissures, contradictory and difficult of explanation. 

 They need not wonder, therefore, at being yet 

 unable to understand the wider question connected 

 with its range and transmission. Passing to the 

 local phenomena, Major Powell's telegram stated 

 that the earthquake had been accompanied by land- 

 slides and crevasses, but by no sea-wave. Fissures 

 opened in the ground, some of which ranged north 

 and south, others east and west. From these fissures 

 mud and sand were ejected. Several telegrams 

 spoke of stones falling from the air, and although 

 there was plainly much exaggeration in these accounts, 

 it was probable that some stones were ejected far 

 into the air, and subsequently fell to the ground. 

 Later telegrams spoke of an unusually high tide, 

 which did some damage over the low lands of which 

 Sullivan's Island is composed, and there was probably 

 some connection between this and the earthquake, as 

 the tides were then the neap tides. 



Accounts varied as to the direction in which the 

 vibratory motion of the earth travelled near 

 Charleston, but as was often the case near the 

 earthquake centre, there was evidence of a twisting 

 movement. One interesting point in connection 

 with earthquakes was the influence they had on wells 

 and springs, and in these respects the American 

 earthquake had had important results. Water now 

 stood where none occurred before, and in certain 

 places springs had been dried. The strangest state- 

 ment, however, on this point was that the Mayor of 

 Bellaplain, Iowa, had telegraphed to Iowa for an 

 engineer to change the course of two gigantic rivers, 

 formed by a phenomenal water burst, which were 

 running at the rate of twelve miles an hour, causing 



much destruction of property. In boring a 4-iru 

 artesian well at a depth of 180 feet, the water had 

 been forced several hundred feet into the air, and 

 the stream had increased until it was sixteen inches 

 in diameter, the upward force equalling that of 

 dynamite. The natural gas wells of Pennsylvania 

 had been affected, and at one town (south side 

 Pittsburg) the factories had been left in darkness 

 through the natural gas supply failing. 



The most interesting fact, however, was that stated 

 in the newspapers about the Excelsior Geyser in the 

 Yellowstone, which had been quiet for four years, 

 but which had spouted violently since Friday, 

 August 27. Torrents of boiling water were thrown 

 up three hundred feet into the air. The geyser 

 was strongly affected long before the earthquake 

 itself was apparent in the Western States, and whea 

 only slight premonitory shocks were apparent in the 

 Eastern States. 



In some telegrams which had been published, it 

 was stated that Mr. M'Gee was inclined to regard 

 the earthquake as due to the gigantic slidings of 

 part of the earth's crust towards the sea, but that 

 his detailed observations of the fissures near Charles- 

 ton presented some difficulties in the way of this 

 explanation. If such an exceptional explanation 

 were the correct one, some important changes of 

 level would be expected near the coast ; but this 

 had not been the case. It was too early yet to 

 theorise on this side of the Atlantic, but at present 

 the earthquake seemed best explained by referring 

 it to some widely acting seismic disturbance, indica- 

 tions of which were previously given by the geysers 

 and by premonitory earthquakes in South Carolina. 

 It would probably be found, however, that its range 

 and local intensity had been controlled by the distri- 

 bution of the rock masses, or by old lines of earth 

 movement and earth weakness. 



THE CARBONIFEROUS LIMESTONE OF 

 THE SOUTH WALES DISTRICT. 



By W. H. Harris. 



SITUATED about mid-channel between Cardiff 

 and Weston-super-Mare are two islands, known 

 as the Flat and Steep Holmes ; they are both masses 

 of carboniferous limestone, and their presence here 

 may be taken as indisputable evidence of the original 

 continuity in this direction of the now widely -sepa- 

 rated coalfields of Bristol and South Wales. 



The steep holm is a wild rugged place, with wall- 

 like cliffs ranging from ioo to 150 feet high. From 

 these the turf-covered summit rises like a saddle-back 

 for another 50 or 60 feet, so that there is comparatively 

 little level ground to be found on the island. It 

 extends east and west about 1 alf-a-mile, and the 

 average width from north to sout'i may be computed 

 roughly at about 350 yards. 



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