SCIENCE- G OS SIP. 



313 



A Kemarkable Formation. — In workings on 

 the southern border of Dartmoor are some very 

 curious formations, which appear when first seen 

 to be simply lumps of stone ; but when the stones 

 are broken, they are found to be hollow, the cavity 

 being partly filled witli sandy mateiial. Some are 

 almost round, others are long and tapering, while 

 many are so flat that it is difficult to believe that 

 they are simply shells until their hoUowness has 

 been proved by breaking through the crust. Others, 

 again, have been moulded into curious and fantastic 

 shapes. The general colour varies from pink to 

 dark red, but is to a considerable extent hidden by 

 the clay that clings to the irregular surface, and 

 which it is very difficult to remove even by hard 

 scrubbing in water. The roughness of the exterior 

 is caused by the presence of crystals of quartz 

 felspar, etc., and occasionally of very small black 

 crystals. The interstices between the crystals are 

 filled up with sandy material and kaolin, otherwise 

 china clay. If a portion of the shell be removed 

 the inner surface is found to be smoother than 

 the outer and of a uniform colour, but it has 

 sometimes a few crystals adhering. The thick- 

 ness of the crust is about half an inch, but it 

 may reach as much as one and a half inches at 

 the edges, or possibly be so thin in other parts 

 as to break on the slightest pressure. The con- 

 tents consist of sandy clay, which varies from 

 pale yellow to dark red. When a portion of the 

 crust was pounded up in a mortar, and thus reduced 

 to a fine powder, it resembled the material found 

 inside the shell, and was of a deep red colour. The 

 broken bits of crust, however, do not appear red 

 where the fracture has taken place, but are very 

 dark, almost black, and show a distinct crystalline 

 structure. The shells are porous, those found in 

 damp places containing water, which, mixing with 

 the contents, often results in a bright red fluid 

 containing the particles in suspension. The colour 

 is due to the presence of iron, for qualitative 

 analysis shows that the crust is composed of 

 oxides of iron with aluminium and silicon. Speci- 

 mens of these hollow shells may be obtained 

 varying in diameter from two to ten inches, and in 

 weight from a few ounces to as much as seven or 

 eight pounds. These productions were found in 

 one of the china-clay pits at a depth of tvi^enty to 

 sixty feet, and were buried in kaolin and other 

 granite detritus. The clay in which the shells lie 

 is useless for the potteries, since the oxide of iron 

 present in this formation causes the clay to be- 

 come 3rello\v when it is baked. These shells may 

 have been formed by the crumbling away of central 

 parts of solid masses of ore, or perhaps another 

 possible solution may be, that they were formed by 

 the fusing of two veins of ore running close to each 

 other, and at the same time enclosing a quantity 

 of material that by decomposition and contrac- 

 tion resulted in the powder that now fills the 

 cavity to a considerable extent. This powder 

 would, of course, get mixed with particles of the 



surrounding ore, and thus become coloured, the 

 depth of tint depending on the quantity of iron 

 which became disintegrated from the inner surface 

 of the crust. The stones would thus be composed of 

 two separate portions similar to the two halves of a 

 walnut shell. The grounds for this explanation 

 are : (1) A line can usually be traced round the 

 crust dividing it into two parts, and thus indicating 

 where contact and union took place. This line 

 does not indicate the weakest portion of the shell, 

 for when broken they do not separate at the line ; 

 (2) many of the shells are very much flattened, so 

 that the opposite faces are, roughly, parallel ; (3) 

 parallel veins of ore .-imilar to that which composes 

 the shells may be found in the matrix from which 

 the specimens were taken ; (4) U -.shaped fragments 

 of ore may be seen which are suggestive of this 

 mode of construction. These facts do not make 

 their origin perfectly clear, and any other ex- 

 planation of their formation would be interesting. 

 The photograph shows a selection of the shells to 

 illustrate their main features. The one referred 

 to above is quite remarkable, and reminds one so 

 forcibly of a pitcher that it might be put down as 

 a production of the ancient inhabitants of Dart- 

 moor were it not for the fact that it was found 

 about 40 feet under the surface and buried in clay. 

 This pitcher is 9| inches high and 6J inches wide, 

 and weighed 5 lb. when emptied. The central 

 one at the bottom has resting on it the iDortion 



broken off to remove the contents. The circular 

 one in the right-hand corner has not been opened : 

 it is a flat one, and shows along its edge a line, 

 very distinct in places, which clearly marks it off 

 into two nearly equal parts. The central top one 

 is only 2 inches in diameter. — A. Terry Munday, 

 Cornwood Vicarage, Ivyindge, Devon. 



Clarence Kinc4. — We regret to notice the 

 death of this eminent geologist, who was for a 

 short time Director of the Geological Survey of the 

 United States. The most important undertaking 

 by him was in connection with the geological ex- 

 ploration of the fortieth parallel. The main por- 

 tion, which was published during 1876 and 1877, 

 included, besides various reports, the geological 

 and topographical atlas of the Rocky Mountains, 

 the Green Eiver and Utah Basins, and the Nevada 

 Plateau and Basin. In later years his most im- 

 portant work was a paper on the age of the earth, 

 which appeared in the annual report of the 

 Smithsonian Institution for 1893. His death took 

 place on December 24th last. 



