266 Prof. A, E. Nor dens Jdold — Geology of Spitzbergen. 



during far longer periods of time extending even to hundreds and 

 thousands of years. 



In consequence of the great expansion coefficient of ice, these 

 changes must be further accelerated if the porous earthy layer has 

 been completely soaked with water, which is then frozen, and in that 

 case the cracks caused by the contraction of the mass are speedily 

 filled with new ice. It is therefore only what we might expect, to 

 find the Tertiary sandy and clayey strata, which have been thus 

 acted on by water and ice, more dislocated and contorted than the 

 older rocks lying at a depth, which the yearly changes of temperature 

 scarcely reach in a sensible degree. 



X. Post-Miocene and Quaternary strata. — All the fossils found in 

 the foregoing strata show that Spitzbergen, during former geological 

 ages, enjoyed a magnificent climate, which indeed was somewhat 

 colder during the Miocene period, but was still favourable for an 

 extraordinarily abundant vegetation, much more luxuriant than that 

 which now occurs even in the southern part of Scandinavia ; and I 

 have in these strata sought in vain for any sign that, as some geo- 

 logists have of late endeavoured to render probable, these favourable 

 climatic conditions have been broken oif by intervals of ancient 

 glacial periods. The profiles I have had the opportunity to examine 

 during my various Spitzbergen expeditions would certainly, if laid 

 down in a line, occupy an extent of a thousand English miles ; and 

 if any former glacial period had existed in this region, there ought 

 to have been some trace to be observed of erratic blocks or other 

 formations which distinguish glacial action. But this has not been 

 the case. In the strata, whose length I have reckoned above, I have 

 not found a single fragment of a foreign rock so large as a child's 

 head.^ The round nodules in. the Triassic and Jurassic strata are 

 clearly concretionary formations, which contain the same fossils as 

 the surrounding strata. 



It would be of great importance to discover strata which would give 



^ The only certain sign of glacial formations, perhaps, is a block of considerable 

 size, which has been transported some distance from its original position. 



In the deep ravines formed by streams, which in Xorth-west Greenland cut through 

 first the sand beds formed during the glacial period, lower down the Miocene, not 

 glacial sand beds, we have an excellent opportunity of seeing the difference between 

 them, which is very noticeable, inasmuch as erratic blocks are never absent in the 

 former, but always in the latter. On the other hand, I am convinced that sharp- 

 cornered stones, or stone fragments inclosed in considerable quantity in a bed of 

 sand or clay (so-called Krosstensgrus), by no means afford certain e\idence that it is 

 of glacial origin. In this case the mistake is fallen into, as in so many other 

 geological questions, by concluding, because on one occasion a cause A produced an 

 effect B, that the effect B is always produced by the cause A, Gravel with sharp- 

 cornered stone fragments is found, at least in the countries where frost tends to break 

 up the rock surface, always at the foot of steep mountain sides clear of vegetation, 

 and on Spitzbergen also on the flats, which in many places surround the foot of a 

 mountain, extensive tracts, where the ground consists of such a gravel-bed formed 

 by frost, which is increased by eveiy spring flood, and then, being drenched with 

 water, is exceedingly difficult to cross, and very destructive for the shoes. If I 

 except a breccia, belonging to the Hecla Hook formation, which is found in many 

 places, for example at the mouth of Bell Sound, there does not occur in the sedi- 

 mentary strata of Spitzbergen or elsewhere any appearance of old Moraine gravel- 

 beds. 



