December 18, 1885.] 



SCIENCE. 



549 



disturbances due to trap-dikes and faults. The 

 dip of the coal-seams is in general S. E. 25-30°. 



Several new analyses of the coal of this area are 

 presented, some of them being of average samples 

 from large quantities. The coal is ' bituminous,' as 

 is shoAvn by the following average of a large num- 

 ber of analyses : volatile matter, 30 ; fixed carbon, 

 54 ; ash, 12 ; sulphur, 3.6 j)er cent. At times the coal 

 has been altered to a semi-anthracite, and even to 

 a natural coke, by the heat of trap-dikes. 



The expense of working the coal in seams 2 feet 

 thick is estimated at $1.50, and in seams 3 feet 

 thick at $1.20, per ton. In the mines of Tennessee 

 and West Virginia, with which the North Carolina 

 coal comes in competition, mining is carried on at 

 the rate of about 65 cents per ton. Combining 

 these figures with the cost of transportation, it is 

 shown that there would remain a sufficient 

 margin in favor of Deep Eiver coal to command 

 the market in eastern North Carolina. This is 

 favorable to the development of the Deep River 

 deposits : still the fact that these mines have not 

 been worked for many years is significant. 



The Richmond coal-field, which is of the same 

 age and of the same general character as the Deep 

 River deposit, but in which coal occurs in much 

 thicker seams, and in general is of better quality, 

 has also been a failui'e, when the mining opera- 

 tions of the whole field are considered. It is evi- 

 dent, therefore, that there must be some sufficient 

 reason why mining in these fields, which are in 

 close proximity to good markets, has not suc- 

 ceeded. Dr. Chance enumerates some of the 

 more obvious difiiculties that present themselves in 

 the Deep River area : there are variations in the 

 thickness and quality of the seams, faults, trap- 

 dikes, presence of explosive gas, water, spontane- 

 ous combustion, and absence of coal from certain 

 areas. Nearly aU of these obstacles are probably 

 much more difficult to surmount in these mines 

 than in the great coal-fields to the west, with which 

 the North Carolina coal comes in competition. 

 To the present writer, who has recently examined 

 aU of the triassic areas south of the Potomac, it 

 appears that the difficulty in the way of econom- 

 ical mining in the various triassic coal-fields arises 

 mainly from the structure of the deposits. All of 

 these areas are extensively faulted, and are trav- 

 ersed by an extended system of trap-dikes. Along 

 the faults the coal has been so completely crushed 

 that it is usually of httle commercial value. At the 

 same time, the continuity of the beds has been 

 broken, and their dip disturbed and rendered 

 irregular. 



This wide-spread disturbance renders the expense 

 of working the coal extremely uncertain, mainly 

 on account of the difficulty of following faulted 



beds. The numerous trap-dikes that intersect the 

 triassic areas north of the Potomac have caused 

 disturbances which are even more injurious to the 

 coal-deposits than the effects of faulting. The 

 dikes are frequently accompanied by a displace- 

 ment of the beds on either side, and also by an al- 

 teration of the adjacent coal. At times the coal 

 in proximity to the dikes has been ruined by the 

 heat ; but in some instances, however, a natural 

 coke has been produced which is more valuable 

 than the unaltered coal. Trap-dikes more than a 

 few feet thick are so expensive to penetrate that 

 they are practically insurmountable obstacles when 

 met with in coal-mines. This was the case in cer- 

 tain mines formerly worked at Gulf. Again, the 

 trap sometimes penetrates the coal-bearing strata 

 in intrusive sheets, approximately parallel with 

 the planes of bedding, and in these even more 

 troublesome to the coal-miner than when it forms 

 vertical dikes. 



A study of the numerous mining operations 

 that have been carried on. commonly with failure, 

 in the Richmond coal-field, would illustrate the 

 peculiar difficulties to be expected in the Deep 

 River basin. The lack of success in so many min- 

 ing ventures in the triassic areas south of the Po- 

 tomac, owing to the disturbances that have affected 

 the coal, proves conclusively that raining should 

 not be undertaken in the triassic coal-fields of the 

 south without a careful preliminary examination 

 with a diamond drill of the entire property that it 

 is proposed to work. The quantity, quahty, and 

 position of the coal should be accurately deter- 

 mined before expensive mining operations are be- 

 gun. With these precautions, it is probable that 

 portions of the Deep River coal-field can be devel- 

 oped with profit, but it is safe to predict financial 

 failure for those who begin miniiig with the ex- 

 pectation of working continuous coal-seams in the 

 manner followed in West Virginia and Pennsyl- 

 vania. 



The coal-deposits on Deep River were also exam- 

 ined by Dr. Chance, who pronounces them to be 

 valueless for commercial purposes. 



This report will be of value to those interested 

 in the coal-deposits of North Carolina, but it con- 

 tains little that can be considered as a contribution 

 to geology. I. C. Russell. 



THE AMERICAN FERRET. 



Although the philosophical biologist measm-es 

 the importance of a species by the fight it throws 

 upon the problem of the science wliich he culti- 

 vates, there are certam animals and plants wliich, 

 while not intrinsically of unusual importance, 

 enjoy a special prominence on account of their 



