C. A. White — Puget Group of Washington Territory. 445 



quiti rivers in California, of the Willamette in Oregon, and of 

 Puget Sound (known as Puget Sound basin) in Washington 

 Territory. The latter valley was the scene of deposition of the 

 coal-bearing series of strata which is characterized by the mol- 

 luscan fauna already mentioned. 



Mr. Willis describes this formation as consisting of " alter- 

 nating beds of yellow and fine grained sandstones and very 

 fine arenaceous shales interstratified with many beds of carbon- 

 aceous shale and coal ; the individual strata of sandstone and 

 shale, from 20 to 200 feet thick, maintain the same general 

 character wherever observed." He further says that a section 

 measured near the town of Wilkeson in Puget Sound basin 

 " gives a minimum thickness of 13,200 feet, with a probable 

 maximum of 14,500 feet." The surprise that one feels upon 

 learning of the extraordinary thickness of this estuary deposit 

 is increased by Mr. Willis's statement that, so far as he could 

 observe, the contained molluscan fauna ranges vertically through 

 the whole formation. 



This is surely a remarkable deposit for one of estuary origin, 

 but it is so regarded in consideration of the following facts : 

 No trace of an open sea fauna has been found in it, while all 

 the molluscan remains that have been found in it are related 

 to estuary forms. These remains embrace species of the Cor- 

 biculidee, the members of which family are known to range 

 from brackish to fresh waters. These forms are associated 

 with certain others whose living congeners are known to range 

 from marine to brackish waters but not into fresh waters ; and 

 the strata of this deposit contain an abundance of vegetable re- 

 mains, which doubtless came from local swamps and adjacent 

 shores. 



No specimens of this fauna have yet been discovered beyond 

 the present limits of Puget Sound basin, nor in any other for- 

 mation than those from which Professor Newberry's collection 

 was made. But if, as is inferred from a general similarity of 

 lithological characters, the absence of marine fossils, the pres- 

 ence of coal beds and of identical species of plant remains, and 

 from similarity of position with relation to older and later for- 

 mations, the deposits which are found upon the eastern side, as 

 well as within the body, of the Cascade range in southern 

 Washington Territory, constitute parts of the same formation 

 which is found upon the western side, the scene of its deposi- 

 tion extended much beyond the limits of Puget Sound basin. 



This conclusion of course implies that the portion of the Cas- 

 cade range upon which those strata are found was not then ele- 

 vated, as was the northern portion, and that the outline of the area 

 within which this deposit was made was very different from 



Am. Joue. Sci.— Third Series. Vol. XXXVI, No. 216.— Dec, 1888. 

 28 



