136 G. M. DAWSON — COASTS OF BERING SEA AND VICINITY. 



The forms of the hills are not rugged or scarped, but they have been 

 cut back into seacliffs of varying height along all the shores. 



There is no appearance of volcanic craters, cones or centers of eruption, 

 nor were any volcanic rocks of surface origin, such as the basalts of the 

 Pribilof and Nunivak islands, seen about these islands. The hills seem 

 to be the residual portions of much more extensive volcanic accumula- 

 tions of some antiquity, of which the greater part has been removed by 

 ordinary processes of denudation. So far as examined, they were found 

 to be composed of rocks generally less basic in composition than the 

 basalts and probably in the main of deep seated origin, but neverthe- 

 less entirely volcanic or eruptive. No raised beaches or terraces were 

 observed, nor were any recognizable instances of travelled bowlders or 

 traces of glaciated rock surfaces seen on the islands of this group. 



The following more detailed notes include the results of examinations 

 made on August 10, 11 and 12, 1891 : 



The cliffs at cape Upright, the eastern end of Saint Matthew island, 

 are in some places about 500 feet in height, ver}^ rugged in form and 

 tenanted by numerous seabirds. The sea has here cut back beyond the 

 crests of a small group of hills, so that the ground slopes away steeply 

 inland from the summit of the cliffs. The rocks are everywhere very 

 much shattered and jointed. They consist of greenish and purplish 

 feldspathic materials, often porphyritic, in many cases evidently clastic, 

 and in one place including a hard, pale greenish tuff. These are asso- 

 ciated with a gray fragmental rock chiefl}^ composed of granitic material, 

 with much epidote and chlorite. This simulates a granite, but contains 

 also angular fragments of the darker porphyrites. Nearly all these rocks 

 are considerably decomposed, and resemble rocks met with in British 

 Columbia, where the centers of eruption of Miocene date have been cut 

 through or exposed by denudation. 



In following the north coast of Saint Matthew island from cape Upright 

 to its deepest indentation, which forms an open bay, where we anchored, 

 a stretch of low land with gravel beach is first passed. Cliffs then border 

 the sea, and are composed of rather massive rocks of dark color, resem- 

 bling those above described. In rounding the most prominent point 

 between cape Upright and the bay, however, a thick stratum of a grayish 

 yellow color is observed in the cliff. This rests with perfect regularity 

 on the darker rocks below, but its upper surface appears to^have been 

 plowed up by the passage over it of the overlying material in a molten 

 state. The general dip of the beds is southward at an angle of about 15°. 

 The light colored material is probably tuff or 'fine volcanic agglomerate. 



From the anchorage westward, the rocks of the north shore of Saint 

 Matthew island, were seen only from the sea. They appeared to be 



