44 THE PENOKEE IROX-B EARING SERIES. 



relation at Penokee gap. Its strike is N. 07° W., and its dip 49° NE, The TTuroiiiau 

 rock lies in absolnte contact with this, not even being separated by a fissnre. Indeed, 

 at one jKiint the siliceous material that formed the Huronian rock had, at tlic time of 

 its deposition, so insinuated itself into the irregnlaiities of the snrl'ace of the gneiss 

 that the two formations are interlocked, and a hand specimen was obtained, one pcntion 

 of which is Laurentian gneiss and the other Huronian schist, the two being, of course, 

 uncoiifoi'mable. It is doubtful whether a similar specimen has ever previously been 

 secured. 



The base of the Huronian series as here exposed is formed by gray and purple 

 siliceous schists, interleaved with which are occasional ])urplish layers of a chiy-like 

 texture. Some of these approach a pipestone and raise the question — which, of 

 course, they are not competent to answer — whetlier they are not tlie approximate 

 equivalents of the pipestones of Barron county, which sustain a somewhat similar 

 relation. 



The general stiike of these schists is N. 55° E., and their average dip about 

 60° NW. By comparison with the Laurentian strata it will be seen that the two 

 formations strike across each other at a large angle and dip in opposite directions. 

 (Pp. 20-27). 



Hunt (T. S.). Special Report on the Trap Dikes and Azoic Roc^ks of South 

 eastern Pennsylvania. Part i. Historical Introdutrtion, Second Geologi(!al Survey of 

 Pennsylvania, volume E. Harrisburg, 1878. 



Contains in a general historical review several brief references to cer- 

 tain of the acconnts of the Penokee-Gog-ebic disti-ict pi-cvioiisly published 

 and above noted. Dr. Unnt had not himself been in tlie district. 



1879. 



Chambeblin (T. C). Annual Report of the Wisconsin Geological Survey for 

 the year 1878. Madi.son, 1879, pp. 5-7. 



Contains a lirief account of the work then still in progress under R. 

 D. Irving in northern Wisconsin, and particularly a statement of the route 

 followed bv Mr. A. 1). Conover in nurking certain additional explorations. 



iRViNct (R. D.). Note on the Stratigraphy of the Huronian Series of Northern 

 Wiscon.sin; and on tlu^ Equivalency of the Huronian of the Marquette and Penokee 

 Districts. Am. Jour. Sci., .".d series, vol. xvil, 1879, pp. 393-398. 



This article calls into (juestion the scheme of stratigraphy for the 

 Penokee district, aboA c (pioted from Brooks, and gives also a preliminary 



