EDMONTON FORMATION 365 



Feet 



Sandy white clay 15 



Hard laminated sandstone, generally persistent 4 



Light clay, occasional sandstones 100 



Laminated reddish sandstone, fossils numerous 5 



Clay and iron-encrusted pebbles, fossils numerous 30 



Sandstone 8 



Light blue-gray clay 70 



408 



Many vertebrate fossils were collected at Big Valley, ranging from near 

 the top to the bottom of the exposures. In the upper 50 feet of sand- 

 stone a few vertebrae of Champsosaurus sp., an occipital condyle of a 

 crocodile, and fragments of a Trionychid turtle were secured, the only 

 representatives of those families seen in the Edmonton formation, with 

 exception of one Trionychid turtle collected near the bottom of the beds 

 at Willow Creek. 



The following invertebrates were secured from a stratum about 100 

 feet above the river: Sphcerium sp., Physa sp., Viviparus sp. related to 

 V. raynoldsanus M. and H., Viviparus sp. related to V. prudentius White, 

 Goniobasis tenuicarinata M. and H., Goniohasis tenuicarinata var., Gonio- 

 basis sp., Campeloma sp., TJiaumastus linnceiformis M. and H. ? In his 

 comments Dr. T. W. Stanton says that ^'^there is nothing characteristic 

 of either Lance or Judith Eiver in this lot and some of the forms are 

 more suggestive of Fort Union." 



Below Big Valley the banks are clean scarped and the beds continue of 

 similar character for several miles. A workable seam of lignite, about 3 

 feet thick, appears near the top of the bank 3 miles below the mouth of 

 Big Valley and a seam, probably the same one, appears again just above 

 Tolman Ferry. The upper part of the beds continues banded in light 

 and dark color, with white argillaceous sandstones interstratified with 

 impure lignite and carbonaceous clays. Iron-encrusted sandstone lenses 

 increase toward the base and the lower strata are composed chiefly of 

 light gray clays. 



From Big Valley down to the end of the formation the upper strata 

 disappear about as rapidly as the fall of the river brings the lower strata 

 to view, so there is no great variation in the height of the banks. Not 

 less than 300 feet of the upper strata have been eroded at Tolman, where 

 the canyon walls are estimated to be 300 feet high. 



Throughout the Edmonton formation water ripple-marked sandstones 

 are common. At a point 2 miles above Tolman Ferry on the left bank 

 there is a bed 100 yards square, and in which four successive series of 

 XXVI — Bull. Geol. See, Am., Vol. 25, 1913 



