NO. 2.] GEOLOGICAL SKETCH BY NANSEN. 



absolutely horizontal ground, and that thus the basalt flows were originally 

 absolutely horizontal. 



The Jurassic deposits ot Northbrook Island beyond Cape Flora, are very 

 little known. They have been examined almost exclusively at Cape Gertrude^. 

 The sedimentary beds here were investigated by Dr. KoettHtz at various heights 

 where they are exposed, from sea-level to 24 m. (80 feet) above, and again 

 from 75 to 150 m. (250 to 500 feet) above. These strata differ remarkably 

 from the strata (clay-beds) underlying the basalt at Cape Flora. „They yield 

 no fossils except fossil wood and lignite, and are for the most part composed 

 of sand in thin layers, extraordinarily variable in colour. Among the sand 

 layers are many strata containing pebbles of quartzite, radiolarian chert, jaspis, 

 „ironstone-nodules", etc. „Thin strata of soft clay-shales also occur frequently. 

 Bands of lignite, or of brown, decomposed fossil wood, an inch or two thick, 

 are frequent. Here and there the sand-strata seem to harden locally into a 

 very hard, calcareous, grey sandstone, in which ripple-marks were found. These 

 sandstone masses protrude from the inclined section in great bosses 2". 



The only part of the Jurassic beds at Cape Flora to which in my opinion 

 these sediments of Cape Gertrude may correspond, is the strata of sand with 

 black carboniferous seams (fig. l,b) in the bank above the shore south of Elm- 

 wood (see p. 12 (b)), which are probably underlying the 150 to f 75 m. (500 to 

 570 feet) thick clay beds containing Jurassic marine fossils. As far as we 

 know, the horizon of these clay beds does not seem to be represented at Cape 

 Gertrude, the sediments of which, in my opinion, may be of an earlier age, 

 and the horizon of the highest of them the same or similar to that of the 

 sand strata with carboniferous seams south of Elmwood ^. This would imply 

 either a fault or a dip in the lower Jurassic strata (which has also actually 

 been observed going NNW. see p. 13.) which has been anterior to the discharges 

 of the basalt above. The dip or fault in these deposits, which have evidently 

 been formed in very shallow water, or to some extent perhaps in freshwater, 

 may also very well be anterior to the deposition of the Jurassic clay beds 

 containing numerous marine fossils, found at Cape Flora. 



1 Newton and Teall, L c. 1897, p. 503. 



2 Communicated by Dr. Kcfitllitz. 



3 Seams of lignite, or similar strata of sand (possibly of freshwater origin) have not been 

 found at any higher level (45 feet above the sea) or in any other locality at Cape 

 Flora, as far as I know. 



