192 The American Geologist. September, i89» 
as well as such voluminous local floras, was attained, appears 
to have necessitated a refinement in species separation that 
seems in many cases to be impracticable if not impossible of 
satisfactory recognition. 
(6) An apparent angle between the horizontally bedded 
Tertiary basalt and the supposed Upper Cretaceous sediments 
west of Niakornat may warrant the hypothesis of Tertiary 
erosion in that vicinity. On the south coast, at Atane and 
Patoot, the Tertiary sediments are thought to be thinner than 
at Atanikerdluk, which lends further support to this suppo- 
sition. 
(7) The entire region of the west coast of Greenland in 
which Mesozoic or Tertiary sediments are now^ found is 
capped by a great number of superimposed, approximately 
horizontal, non-columnar basalt beds of varying thickness and 
of great extent. Frequently 3,000 feet of this basalt cap re- 
mains, while at Kilertinguak (6,250 feet above tide) over 4,000 
feet is preserved. 
In certain regions numerous dikes intersect at varying 
angles the Cretaceous, Tertiary, and even the lower portion of 
the basalt cap, and are frequently found both forking and in- 
tersecting. Intruded basalts are not rare, especially in the 
Tertiary. The peridotite intrusive beds, about 350 feet thick, 
back of Kaersut are probably of Tertiary age, as are also the 
other high intercalated basalts. 
At the time of the great elevation of the region, probably 
in the late Tertiary, the basalt cap, which, judged by the de- 
velopment on Unbekanntes island, may have exceeded 7,000 
feet in thickness, most probably extended in an unbroken 
sheet from the south of Disko island north to beyond the 
Svartenhuk peninsula, a distance of 250 miles. 
(8) The dissection of this great basalt sheet, the develop- 
ment of the Vaigat, the Umanak fiordal system, the isolation 
of Disko — in fact, approximately the present land topography 
of this coast — were accomplished at a much greater elevation 
during Pleistocene time. 
(9) Evidence of post-Pleistocene subsidence, with Arctic 
climatic conditions, is found in the presence of recent Arctic 
marine shells occurring in terraces at an elevation of from 100 
to 150 feet above tide. In the old crystalline region much 
