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lion of the series, which would imply its contemporaneous origin with 

 the strata. 



The form and position of the veins is rarely such as to justify this 

 view. Instead of lying in uniform thickness between the walls of 

 the adjacent rock, and with surfaces of slight irregularity, we find 

 the auriferous veins in most cases very irregular in their forms, at 

 one point having a thickness of several feet, at another very near to 

 the former, contracting so as only to measure a few inches across. 

 Again, in many cases the vein divides, and the separate portions af- 

 terwards unite or send off other branches. 



The bounding surfaces too, instead of being nearly uniform, as in 

 the strata of the neighbouring rocks, are rough and broken, sending 

 off numerous small veins of quartz into the enclosing strata. 



In Morton's mines, the width varies from seven feet to five or six 

 inches. In Booker's the vein forks, thins, and as frequently widens. 

 At the Union mines on the Rappahannock, the breadth varies in 

 some cases from six inches to nearly three feet. 



In fact, from the dimensions of the vein at any assumed point, no 

 certain inference can be drawn with regard to its extent at other 

 and remote positions. This irregular structure, while it diminishes 

 confidence in the constancy of a large and fertile vein, at the same 

 time furnishes grounds for continuing the examination and prosecu- 

 tion of one, which by its contraction has become of little or no va- 

 lue, as an enlargement at a small depth beneath, may reveal an abun- 

 dance of productive rock. 



Another fact of some practical importance, and one which, together 

 with those above stated, has a direct bearing upon the question of 

 the origin of the auriferous veins, is this, that although in the main, 

 the dip and direction of the vein conforms with those of the enclosing 

 strata, the correspondence is far from being exact, and in many in- 

 stances, while the inclination of the neighbouring strata remains un- 

 changed, that of the vein undergoes very striking alteration. At 

 Morton's mine, already referred to, the dip near the surface is about 

 20°, while at some depth beneath it becomes 45° ; and similar in- 

 stances of variation might be adduced by reference to other locali- 

 ties. 



It would thus appear, that these numerous veins of quartz are not 

 to be regarded as deposites coeval with the regularly stratified rocks 

 among which they are found, since in that case their position and 

 structure would exhibit a like degree of uniformity, but as matter 



