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THE JOURNAL OF GEOLOGY.

large area of quartz-porphyry in the Great Smoky Mountains in Yancey Co., N. C., during the past summer.

The geological reports on South Carolina, by Lieber, describe a great development of igneous rocks which cross the state in the continuation of the North Carolina volcanic belt and which are themselves very probably in part of surface origin. His first report for 1856, which treats of Chesterfield, Lancaster, Chester and York counties, mentions among other more coarsely granular igneous rocks, eurite or quartz-porphyry, aphanitic-porphyry and melaphyre.[1] The counties of Union and Spartanburg, dealt with in Lieber's second report, are much poorer in igneous rocks, though he here adds the types schistose aphanite and minette. On the geological map of South Carolina, published by the Department of Agriculture in 1883, the belt of aphanitic greenstones and porphyries is shown to be continuous across the state in a southwest direction, and the statement is made that the greenstones predominate toward the north, and the porphyries toward the south, in Abbeville county.

Upon an expedition undertaken at the instigation of the writer, Prof. S. L. Powell of Newbury, S. C., found at Chester abundant eruptive rocks (granites and diorites), but none of unmistakably volcanic origin. At Lancaster, on the other hand, he found amygdaloids and felsites, showing distinct flow-structures which are certainly of igneous origin and could only have solidified at the surface.

In Georgia and Alabama nothing can be stated with certainty in regard to ancient volcanic rocks as the crystalline portions of these states have not as yet been petrographically invesitgated. The porphyry area of Abbeville county, S. C., is probably continued into Georgia. One single specimen of quartz-porphyry showing a beautiful micropoikilitic structure, collected in northwestern Georgia near the Tennessee line, has already been mentioned by the writer.[2] A box of specimens kindly sent

  1. ↑ Report on the Survey of South Carolina for 1856, 2d ed., Columbia, 1858, p. 31.Lieber had the German ideas regarding igneous rocks and their nomenclature. His "trachyte," "domite" and "phonolite" are probably fine grained varieties of the acid volcanic types.
  2. ↑
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