GEOLOGY. 309 



a wild herbivorous animal from a tame one ; and this is a certain in- 

 crustation of brown tartar upon the teeth." This deposit he did not 

 find upon the porcine relies at the Wrekin, but he fancied, at first, 

 that he detected it upon the teeth of the fossil bovine remains in Ire- 

 land. However, after examining the latter more carefully, he noticed 

 a ferruginous deposit from the peat, which might easily be mistaken 

 for the incrustation of brown tartar. "In the one case there would 

 be traces of parasitic life under the microscope, not so in the other 

 case. The incrustation from the peat covered the whole tooth, at 

 least as much of it as was not of the bony alveolus ; whereas the tartar 

 incrustation was only upon that portion of the tooth that had not been 

 imbedded in the gum. The latter was conspicuously present in sundry 

 teeth of Megaceros hibernicus and of Cervus elaphus." We presume 

 that for this reason Mr. Blyth regards these species as belonging to 

 the category of domesticated animals, but we wish the evidence was a 

 little more convincing. ^Dublin Quarterly Journal of Science. 



Native Zinc has been discovered in a basalt from a locality near 

 Melbourne, in Australia. 



Missing Sedimentary Formations. The Journal of the Geological 

 Society has a full paper on this subject. Although it has been long 

 known that formations are frequently absent from their places in the ver- 

 tical series of sedimentary rocks (such as lias between oolite and trias, 

 &c.) yet little notice has been taken of the fact, except mere allusions. 

 Dr. J. J. Bigsby was therefore led to reduce to order a great deal of 

 information on the subject, collected from the writings of the most emi- 

 nent geologists. The missing formations hold a high and important 

 place as a result of one of the constructive processes of the earth's crust, 

 and the work is still going on. He concludes that they are among the 

 several consequences of emergence and immersion, themselves the effect 

 of one of the great cosmic agencies, oscillation of level, which may be 

 gradual or paroxysmal, through all the degrees of velocity and energy. 

 Those interested in the subject will rejoice in the details given respecting 

 these " leaves torn out from nature's volume," gaps or blanks, which " by 

 their magnitude and number, become a great feature in the earth's crust, 

 expressive of unity of design in time and space." 



Conversion of Wood into Coal under Pressure. We have received 

 from Mr. Robert Safely, of Cohoes, New York, an account of the con- 

 version of a portion of the wooden step of a turbine water-wheel into a 

 very compact coal resembling closely in texture and appearance ordinary 

 mineral coal, along with a specimen of the coal. The step was of oak, 

 and about ten inches through ; and when taken out, the whole surface 

 was covered with, a layer of coal. The charring was a consequence of the 

 water pipe which lubricated it becoming clogged with dirt. Mr. Safely 

 states further, that the fall of water to which the wood was subjected 

 when it was converted into coal, was exactly 25 feet; and as the diameter 

 of the wheel is five feet seven inches, the pressure on the wheel would be 

 measured by a column five feet seven inches in diameter, and 25 feet 

 high, less what is due to the water striking the bucket at a small angle 

 to the lane of the wheel. The gearing, wheel, shaft, etc. weigh about 

 three tons, which would give for the pressure upon the step, if the whole 

 weight of water was reckoned, about 20 tons. The facts exemplify the 

 formation of coal underpressure, combined with moisture and a moderate 

 heat, and with very slow motion. Sidi mail's Journal. 



