NATURAL SCIENCES OF PHILADELPHIA. 47 



water hole of green slimy liquid, we camp on the west side of the 

 creek. 



While investigating the formation of the bluffs capped with 

 gravel, we find many beautiful moss agates, and numerous flakes 

 and rude stone implements, mixed in tertiary gravel and seemingly 

 coeval with it. 



Oct. 24. Crossing Crow Creek at camp our course is N. 23 and 

 K 11 east. 



On leaving Crow Creek I obtained a complete suite of stone im- 

 plements and rude fragments which occur mixed in a gravel and 

 sand deposit that composes the summit and sides of the low bluffs 

 on the east bank. I found them in the gravel, in the soil, in every 

 kind of position, and sometimes weather beaten or stained by 

 weather and rain. The accompanying gravel is composed of smooth 

 pebbles of quartzite jasper, agate, granite, mica, slate, basalt ; with 

 a few shells and fossil wood, or wood opal ; while in the low grounds 

 at the foot of the bluffs ancient fireplaces, burnt fragments of bone 

 and wood, with flint and agate, chips and implements, almost uni- 

 versally distinct from those on the summit of the low hills border- 

 ing Crow Creek; so much is this the case, that the two seem to 

 point to a distinct era, the later presenting some progress and re- 

 finement even in stone implements. 



The evidences of the oldest and rudest art do not even show 

 traces of fire or fireplaces ; rough implements, irregular piles of 

 pebbles, are all that is left us to show and identify to the observer 

 the obscure seat of a still more obscure barbarism. 



Anotlr si* fact puzzles me, that whenever and wherever on Cache 

 La Poudre, Big Thompson River, Clear Creek, Crow Creek, and 

 Platte River, we find evidences of " Pre-aboriginal" occupation, 

 it is invariably on the low bluffs bordering these valleys, and in a 

 tertiary gravel deposit ; but if we go back in the higher region 

 of the prairies, they almost disappear or present a difference in 

 form or material. 



The shape, the location, the rude barbarism of these first 

 attempts of art irresistibly lead us to compare them to the rude 

 tools of Abbeville in France, or the implements of kerne in Eng- 

 land. I am glad to be able to give a few shells from this place, 

 which will serve to guide us in determining the age of the gravel 

 beds of Crow Creek. 



We are fast nearing the high table-land, between South Platte 

 1872.] 



