68 RECONNAISSANCE IN .NORTHERN ALASKA IN 1901. 



i-hloritif.schi.sts and phylliteson the south, through impure limestone, slate, sandstone, 

 quartzite, and grit, to hard conglomerate on the north. As shown in the discussion 

 of the Skajit, Totsen, Lisburne, and Stuver series, the Endicott Mountains contain 

 two geologic axes, a northern and a southern, both composed Of the older Paleozoic 

 rocks, and. as represented on the "-colonic map and section (PL III), the Fickett 

 series lies essentially in what appears to be a broad trough between these two 

 axes. This trough or syneline. judging from the unconformity of the Fickett 

 series to the Skajit and Lisburne formations, and the difference in character of the 

 sediments, was probably occupied by an arm of the sea in late Paleozoic time, when 

 the axes on the north and the south seem to have stood above sea level; and the 

 sediments of the Fickett series, judging from their calcareous content, were probably 

 in part derived from these Paleozoic land areas. 



Here the Fickett series has a width, or north-south extent, of about 50 miles. 

 On the south its edges appear to rest unconformably on the eroded Skajit forma- 

 tion of the southern axis, as shown in the geologic section, while owing to the fault- 

 ing at the head of John and Anaktuvuk rivers its relations to the older rocks of the 

 northern axis are not definitely revealed. It seems, however, to meet the Stuver 

 series and the Lisburne formation by fault contact, as has been indicated. To the 

 north of this contact, so far as observed in the region of the Anaktuvuk, all trace of 

 the series in place seems to have been removed b} T erosion. To the west, however, 

 beyond the limits of the fault-block system of the Devonian, about 20 miles from the 

 Anaktuvuk, it seems to overlie the Lisburne formation, andprobabh T extends beneath 

 the Mesozoics at the north base of the range. From the occurrence of Carboniferous 

 fossils in the stream gravels it is inferred that the same conditions probably prevail 

 to the east of the Anaktuvuk, but they have not thus far been actually observed. 



Beginning on the south slope of the north axis of the range, the lower part of 

 the Fickett series, as it seems to be, consists of dark shale, schistose slate, and appar- 

 ently some dark limestone, which is succeeded by quartzite, grit, and conglomerate. 

 The sediments in the quartzite, and more especially those in the grit and conglom- 

 erate, though they are often fine, bear a marked resemblance to the vari-colored 

 conglomerate of the Stuver series, from which they seem undoubtedly to have been 

 derived. The quartzite, grit, and conglomerate are hard and flint} 7 , the grains and 

 pebbles being thoroughly united by a siliceous cement. The best exposure of these 

 rocks that was seen is that at Fork Peak, on John River, east of camp July 12, from 

 which point for about 15 miles northeastward, to bej-ond the Anaktuvuk portage, 

 they present a steep face to the northwest, overlooking the upper part of John River 

 Valley. Here the dip is gently south or southeast. Apparently these same conglom- 

 erates and grits were also encountered in the lower reaches of a deeply cut gulch 

 about 20 miles south of Fork Peak, west of the mouth of Hunt Fork. Toward 



