336 E. M. KINDLE RECONNAISSANCE OF PORCUPINE VALLEY 



Pennsylvanian and seems to be the latest Paleozoic horizon which appears 

 in the Porcupine section. 



TERTIARY BEDS 



Beds of Tertiary age occupy a broad north and south belt between the 

 Lower and Upper Eamparts, except where the higher parts of the old 

 eroded masses of Paleozoic rocks project up through them. The north 

 and south extent of this basin, which is called the Coleen basin, after the 

 river draining its northern portion, is unknown. The Porcupine traverses 

 this basin in wide sweeping meanders. The migration of the channel of 

 the river along parts of its course through the basin has left in places low 

 banlfs bordered by recent silts. The westernmost exposures of tlie Ter- 

 tiary beds abut against Paleozoic rocks probably of Silurian age a couple 

 of miles below Coleen river. The exposure here shows the following 

 se-ction : 



Section of Tertiary Beds ieloic Coleen River 



Feet Inches 



d. Green, loosely consolidated, lumpy clay, with numerous dissem- 



inated green and a few black shale fragments 50 



c. Green marl 20 



1). Lignite and interbedded dark shales 14 



a. Dark drab clay and shale, with abundant black shale pebbles. . 50 + . . 



Loose fragments of lignite from this and other similar beds may be 

 seen on the river bars for 100 miles below it. The beds here dip north- 

 east 20 degrees and strike north 20 degrees west. Elsewhere along the 

 river the Tertiary beds are horizontal. IvTo fossils were found below the 

 Coleen river, but higher up the stream Tertiary invertebrates were found. 

 These more easterly outcrops are well exposed on the largest meander in 

 this portion of the river, known as the Fishhook bend, which shows con- 

 tinuous bluffs for 2 or 3 miles, 40 to 100 feet high, composed mainly of 

 finely laminated shale or clay. The dominant color of these beds is light 

 lemon yellow, which is varied by patches of yellowish green, pink, and 

 brownish. At the upper end of Fishhook bend, on the west bank of the 

 river, the following section was measured : 



Fishhook Bend Section 



Feet 



e. Fine sand, soil, and muck (top) 1-5 



d. Coarse gravel and sand 10 



c. Dark carbonaceous clay and old forest bed 0-2 



b. Coarse gravel and sand 15 



a. Soft, finely laminated, drab-colored clay shale, with large ironstone con- 

 cretions in upper part, containing fresh-water bivalves 70 



I 



