Horváth Géza (szerk.): A Magyar Természettudományi Múzeum évkönyve 18. (Budapest 1921)
Éhik, Gy.: The glacial-theories in the light of biological investigation
98 Dr. J. í'.HIK the circumstance that Prof. M ÉHEL Y distinguished there a preglacial, a I.-st and a II.-nd interglacial period. 1 The formation of the boreal or tundra fauna must have taken place already in the Pliocene of the arctic regions. The lemming for instance, — a most typical and still living representative of the tundras, — is well known from the lower Pleistocene strata of Northern Germany, so that its Pliocene occurrence must be taken for granted. This conviction of mine is also born out by the geological profde accompanying the text. (The territory from which the boreal fauna originated is marked by 2a). And now let us see how the migration of this boreal fauna took place in consequence of the ice moving southwards and what kind of paleontological documents has it left back. (See the faunistical enumerations enjoined and the geological profile of the Thiede-beds. Fig. 7.) The ice extending southwards drove also the animals in a southern direction. It is natural that larger boreal animals, able to wander over a good deal of ground, were the first in reaching the southernmost localities, beeing then followed by the smaller mammals, rather attached to the soil, whilst in the immediate vicinity of the ice again larger sized animals will be found. Thus the boreal fauna consisted of three different zones, that situated in the middle differing from the two lateral ones by containing smaller boreal forms, unfit to support extreme changes of climate and consequently inhabiting the middle zone, characterised by rather constant climatic conditions. — On spots indeed where a continuous stratification took place and on which the respective petrifications were conserved up to this day, this triple facies will really occur, 2 as proved by the Sirgenstein- and Thiede-strata. The result of the proceeding ice leaching and covering the earlier habitat of the faunae in question, was that the normal course of stratification stopped there, and even fossils belonging to this period are absent, the regions covered by inland-ice preventing the formation of any settlement. And the same thing can be stated in general, with respect to each successive phase on each spot, reached by the ice, until it attained the limits of its furthernmost expansion. In the vicinity of these limits one ought to be able to discern, besides the temporal also the spatial différenciation of the three mentioned subboreal faunistical zones. But the oscillations in the limits of the huge glaciers and special local circumstances render a due appreciation of such a problem more difficult 1 L. MÉHELY, Fibrinae Hungáriáé. Budapest 1914. 8 Such beds are unfortunately very rare. See with respect to this question the quoted passage of NEHRING, p. 90. footnote 1.
