57 



field upon the Chesterfield side of the river. Tracing the dip of the 

 gneiss rock westward, from the western outcrop of the coal, we 

 find it to be towards the S. E., or beneath the coal field, and this 

 throughout a width of several miles in our course west, until we 

 approach the Beaverdam creek ; here, for a short space, the dip is 

 altered to the west, but the easterly direction is after awhile re- 

 sumed, as we approach Goochland courthouse. Between five and 

 six miles further on, or in the vicinity of Little Lickinghole creek, 

 the dip is over more to the west. These various alternations in the 

 position of the strata, are specified for the purpose of showing how 

 probable it is, that the coal strata within the basin were originally 

 deposited in a valley formed by the meeting of an eastern and 

 western dip ; in other words, upon the edges of the strata com- 

 posing a synclinal axis, and not upon a horizontally placed stratum 

 of the gneiss rock. The former view will help us more naturally to 

 account for the very striking inequalities in the thickness of the bed 

 of coal resting nearly in contact with the ancient surface of the 

 primary rock. Had the ancient rocky floor, upon which the materials 

 that formed the coal were deposited, been the gneiss rock in nearly 

 horizontal stratification, it is hard to conceive how any subsequent 

 dislocations of the whole group by upthrows and downthrows could 

 introduce that remarkable degree of unevenness in the thickness of 

 the coal seams over the small areas for which this coal field is so 

 peculiar. Everything lends countenance to the opinion, that the 

 surface of the primary rock, previous to the deposition of the carbo- 

 niferous matter, was a valley of rolling outlines occupied by 

 hollows and elevations, causing the first layers of matter which 

 were thrown down to be deposited in greater thickness in some 

 places than in others. As the lowest coal seam is separated from 

 the crystalline rock beneath by only a very few feet of shale, and in 

 some cases by none at all, it appears likely that the distribution of 

 the coal was made unequal in thickness from the very commence- 

 ment. There is ample proof that subsequently to the consolidation 

 of an enormous thickness of sandstone over the coal, the entire 

 series of beds, including the underlying primary strata, were reft 

 by a number of extensive cracks, producing displacements of the 

 beds, which combined with the original irregularity in the distribu- 

 tion of the coal itself, has caused the internal structure of this coal 

 field to be one of excessive intricacy. These views are stated for the 

 purpose of indicating the necessity of boring as the best and surest 



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