SKAJIT FORMATION AND TOTSEN SERIES 239 



tered, being finely crystalline, schistose, and often micaceous. Some 

 lasers, becoming more and more foliated, grade into mica-schist. The 

 series occurs in the southern part of the Endicott mountains, where its 

 breadth or exposure in a north and south direction is 15 or 20 miles. 

 Here it rises to a height of more than 5,500 feet, forms some of the 

 highest and most rugged topography of the southern axis, and seems to 

 have a thickness of at least 4,000 feet. 



Structure. — So far as known, the formation has a general east and west 

 strike, parallel with the trend of the mountains. The middle portion is 

 synclinal, while the northern and southern edges are anticlinal. The 

 formation is unconformable with the Fickett series of the north and ap- 

 parently so with the Totsen series on the south, both of which it seems 

 to underlie. In general the dips are gentle, but in some localities fault- 

 ing and folding has been intense. The rocks are cut by the major and 

 minor jointings of the range, with the joint planes sometimes locally fol- 

 lowed by veins of calcite and quartz, containing occasionally a little 

 galena or pyrites of iron and copper. 



Age. — Though the limestone, as noted, is much altered by metamor- 

 phism, it contains imperfect faunal remains, one of which has been 

 identified by Mr Charles Schuchert as probably Meristina or Meristella, 

 referring the formation provisionally to upper Silurian and placing it 

 among the oldest known fossil-bearing rocks of northern Alaska and the 

 northern part of North America. 



TOTSEN SERIES (SILURIAN) 



Character and occurrence. — This series of rocks, including a strip of 

 greenstone schist, occupies an east and west belt 12 miles in width. 

 It occurs to the south of the Skajit formation, which it seems to uncon- 

 formably overlie, while it unconformably underlies the Bergman series 

 on the south. The rocks consist mainly of mica-schist and some quartz 

 mica-schist, in both of which the essential minerals are biotite and quartz. 

 Locally the rock becomes graphitic and in cases carries considerable 

 quartz in small veins and lenticular bodies, some of which may be the 

 source of the placer gold colors found in the gravels. The series is essen- 

 tially of sedimentary origin, but the period of sedimentation seems to 

 have been accompanied by igneous effusives or flows of basaltic character, 

 which were later sheared and schisted with the sedimentary beds, giving 

 rise to greenstone schist, of which the most prominent belt, having a 

 width of several miles, occurs in the southern part of the field. Though 

 on account of deformation and folding there is probably some duplica- 

 tion in the Totsen series, its total thickness, by conservative estimate, is 

 probably 6,000 or 7,000 feet. 



