223 Kansas Academy of Science. 



Description of formation. 



The Pleistocene deposits separate themselves into two groups — 

 those exposed along the strait and those exposed along the Pacific 

 front. Below is a description of each: 



Deposits of the Strait Region. — These deposits extend from 

 Port Townsend all the way to Neah Bay, but are exposed only in 

 patches on the coast west of Gettysburg. The formation is of 

 glacial origin and extends to the islands off the coast; in the for- 

 mation on Protection Island many swamp stages are represented. 

 The formation reaches its maximum thickness along the strait from 

 Port Townsend to Gettysburg, it there being from 200 to 300 feet 

 in thickness. Westward from Gettysburg it thins out to a mere 

 edge. In the interior here, however, there is an abundance of evi- 

 dence of glaciation at every place examined north of the northern 

 extension of the Olympic axis; granite boulders were found 800 

 feet above sea-level near the top of the divide on the La Push-East 

 Clallam wagon-road. Towards Neah Bay there are several pre- 

 glacial streams filled with Pleistocene deposits that have not been 

 recut since then; and almost all of the preglacial streams there have 

 a wedge of Pleistocene material in the old channel on each side of 

 the present channel. One glacial-filled channel about six miles 

 west of the Sekiu river has a large number of granite boulders in 

 it. The formation at its maximum-development localities has its 

 lower member till, a stiff blue clay — probably the equivalent of 

 Willis's Admiralty till of the Paget Sound country. The rest of 

 the formation is roughly stratified sand and gravel. 



From the material at hand, it would seem that the northern gla- 

 ciers, coming against the rock walls of the Olympics in their south- 

 ern advance, were compelled to dump their debris on the low lands 

 aad ia the south margin of the strait depression along their front 

 from Puget Sound west to Gettysburg, though it is probable that 

 the deposits were augmented here by increment from the Olympic 

 glaciers. But from Gettysburg westward, on account of a lowering 

 of the land surface, which will be mentioned later, they passed over 

 the western axis to the Pacific, not only not depositing much ma- 

 terial on the strait side but in many places even scraping the rocks 

 bare of all soil, and, passing over the divide, broke off its top, dump- 

 ing the whole of its debris in the Quillayute-Ozette trough and on 

 the ocean front beyond. 



Deposits on the Pacific Front of ihe Peninsula. — In Pleisto- 

 cene times the whole Pacific front of the peninsula was submerged 

 or partly submerged from Waatch Strait to some distance below 



