368 WHITE AND SCHUCHERT—CRETACEOUS SERIES OF GREENLAND. 
(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 remains, while at Kilertinguak (6,250 feet above tide) over 
4,000 feet is preserved. 
In certain regions numerous dikes intersect at varying angles the Cre- 
taceous, Tertiary, and even the lower portion of the basalt cap, and are 
frequently found both forking and intersecting. Intrudeqd basalts are 
not rare, especially in the Tertiary.. The peridotite intrusive beds, about 
390 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 development on Unbe- 
kanntes 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 development of the 
Vaigat, the Umanak fiordal system, the isolation of Disko—in fact, ap- 
proximately the present land topography of this coast—were accom- 
plished at a much greater elevation during Pleistocene time. 
(9) Evidence of post-Pleistocene subsidence, with Arctic climatic con- 
ditions, 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 farther south the terracing is said to extend to 
300 feet above tide. 
(10) The extent of the more recent uplift is not known, since the re- 
treat of glaciers, the inundation of ancient dwelling sites, and the records 
of tide gauges point to present downward movement observable within 
historical time. 
