232 NATURAL SCIENCE [October 1898 



more closely to the higher Cretaceous floras, such as that of the 

 Laramie. The Patoot series may perhaps be safely interpreted as 

 constituting a palaeontological as well as sedimentary transition 

 from the Atane series to the Tertiary. The thickness of the Atane 

 and Patoot series (Senonian) is not less than 1300 feet and may 

 considerably exceed this. 



Tertiary and later Geology of W. Greenland 



Many plants from Atanikerdluk were referred by Heer to the 

 Miocene, but are now generally admitted to be Oligocene, and 

 Messrs White and Schuchert suggest that they may even be of 

 Eocene age. They further remark that the distinction between the 

 floras of Heer's three Cretaceous series rests largely on minutiae of 

 systematic description that cannot be upheld, a view that will 

 doubtless be shared by most palaeobotanists. 



There is some evidence for Tertiary erosion west of Niakornat. 

 After this the entire region was covered by a great number of super- 

 imposed, approximately horizontal, non-columnar basalt beds of 

 varying thickness and of great extent. Frequently 3000 feet of 

 this basalt cap remains, while at Kilertinguak (6250 feet above 

 tide) over 4000 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 intersecting. Intruded basalts are not rare, especially 

 in the Tertiary. The peridotite intrusive beds, about 350 feet 

 thick, behind 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 Unbekanntes Island, may have 

 exceeded 7000 feet in thickness, most probably extended north- 

 wards in an unbroken sheet from the south of Disko Island to 

 beyond the Svartenhuk peninsula, a distance of 250 miles. 



The dissection of this great basalt sheet, the development 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. 

 Evidence of post-Pleistocene subsidence, with Arctic climatic condi- 

 tions, is found in the presence of recent Arctic marine shells occur- 

 ring 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. The extent of the more 

 recent uplift is not known, since the retreat of glaciers, the inun- 

 dation of ancient dwelling-sites, and the records of tide-gauges 

 point to present downward movement observable within historical 

 time. 



