418 Olaf Holtedahl — New Feature* in the 



Bay, we observed that there existed no simple boundary line 

 between the large area of granites and gneisses in the north- 

 west and the Heclahook phyllites, mica schists and quartzites 

 farther south. On the contrary, we found the granitic rocks 

 to occur as intrusive bodies in the metamorphosed sediments 

 and to be therefore younger instead of older than the latter. 

 We have here partly compressed igneous rocks, intruded before 

 the intense folding of the Heclahook was finished, and partly 

 unaltered granites of various types, of a somewhat later age. 

 In these occurrences we have a striking parallel to the condi- 

 tions in the northwestern part of the Scandinavian Peninsula, 

 where in late years more and more of the granites and gneisses, 

 previously regarded as of Archean age, have been proved to 

 be younger than the metamorphosed sediments that probably 

 are of Cambro-Silurian age. 



As for the Heclahook system, we cannot here go into detail. 

 We have worked a good deal with these widely distributed 

 rocks, formerly very little known in our region, and found 

 them to consist of a great number of different types of sedi- 

 ments. We have often met with conglomerates which, in at 

 least one case, indicated the existence of dry land at one period 

 of Heclahook time. The strike is generally NNW-SSE. 

 Unfortunately, we, like earlier geologists, have not succeeded 

 in finding fossils in this system, so we still have to rely on com- 

 parisons with Scandinavia and with Bear Island, where young 

 Ordovician fossils are found in similar rocks, thus fixing the 

 age of at least a part of the Heclahook as Ordovician, although 

 the whole series may have representative formations of Cam- 

 brian to Silurian time. On the other hand, new evidence for 

 fixing the uppermost possible chronological limit of the Hecla- 

 hook has been obtained by our studies on the younger sedi- 

 mentary series. 



For their great thickness and wide distribution, the Devonian 

 strata of Spitzbergen have been previously very little studied. 

 It was known that the system consisted chiefly of red and green 

 sandstones in which were found a few placoderm fishes, in- 

 dicating Lower Devonian age, a large Leperditia, and undeter- 

 mined plant remains. Then there had been found in one place 

 a few Upper Devonian fishes, better plant remains, and an 

 Estheria. Finally, a series of grey slates occurring at Grey 

 Hoek, with new forms of lamellibranchs, had also been referred 

 to the Devonian, although the exact stratigraphical position 

 was unknown. The total thickness of the Old Red type of the 

 Spitzbergen Devonian, the Grey Hoek beds not included, was 

 estimated to be at least 1200 m., and perhaps more than 1500 m. 



We have devoted a great deal of time to the Devonian, and 

 hope to have established the chief features in its stratigraphy. 

 They may be summed up as follows : 



