232 The American Geolo(jist. April, 1897 
of the shores oC Orchard point. On the north shore, as I am 
informed by Mr. F. H. Whitworth of Seattle, the same eruptive 
belt is well exposed to a hight of over 100 feet, maintaining 
the same prominence as at Rich's passage. 
The lithological composition and physical construction of 
the dyke as exhibited within compass of the quarry are ex- 
tremely varied. The bullc of the mass may be described as a 
greenish hornblendic aggregate, granular and spherulitic, and 
in certain distinct divisions partially brecciated, and crumb- 
ling on weathered surfaces. Aphanitic material in schistose 
form constitutes other distinct divisions. Olivine, likewise 
present, is not without significance in connection with the 
volcanic origin of the mass. 
The formation developed south of Georgetown on the Du- 
wamish, is of tlie same lithological type and divisional con- 
stitution, and is doubtless a survival of the same eruptive 
belt, to the extension of which is to be ascribed the upheaval 
of the Tejon series. In tracing that survival to the southeast. 
I shall take further occasion to refer to its advanced decay 
from weathering. 
On the north side of Blakely harbor, cemented gravel or 
conglomerate, made up of pebbles of crystalline rock, occupies 
the low shores on both sides of Blakely point. Blakely. rock, 
at the entrance of the harbor, is a survival of the same cement- 
ed gravel — otherwise practically baseleveled and preserved 
above tide only in isolated masses in place. Divisional planes 
and courses of differentiated material serve to indicate a 
thickness of several hundred feet with strike and dip conform- 
able to the underlying Tejon series on the opposite side of the 
harbor. Hence the inference that the cemented gravel was 
upturned on the flanks of that series. A few hundred feet 
north of Blakely point the cemented gravel gives way to drift. 
The aspect of the rock which sets in just south of George- 
town is casually that of a greenish, pebbly, clastic aggregate, 
cemented by similar material of finer consistency. This ap- 
pearance, however, is deceptive. Kaolinization and peroxida- 
tion of feldspathic and ferrous silicated contents respectively 
have resulted in almost complete disintegration of weathered 
surfaces. A key to the normal condition of the mass under 
cover is atl'orded by a ledge obliquely crossing the plank road 
