206 GLACIAL HISTORY. 



Very scanty information is given in other countries foreign 

 to Switzerland respecting the flora of the drift period. The 

 tuffs of Cannstatt, near Stuttgart, constitute the most impor- 

 tant locality for such remains. They have as yet furnished 

 twenty-nine species, three of which are extinct, namely : the 

 mammoth oak, with its obtusely and widely lobate leaves, 

 6 inches broad, and oval acorns nearly twice as large as those 

 of the Quercus pedunculata ; a poplar (Populus Fraasii, Heer) 

 with large cordate leaves, the edges of which are only faintly 

 undulated; and a walnut-tree which resembles the American 

 species Juglans nigra and cinerea in the toothed pinnae of its 

 leaves. 



Among the species which still inhabit the same region as the 

 lignites Prof. Heer remarks the red fir, the white birch, the 

 hazel, and the sycamore ; and the formation of the forest was 

 also assisted by the white fir, the aspen, and the silver poplar, 

 the pedunculated oak, the hornbeam, the elm, the lime-tree, and 

 the spindle-tree; whilst the undergrowth consisted of several 

 willows (Salix monandra, fragilis, aurita, viminalis, and especi- 

 ally Salix cinerea) , the cornel (Cornus sanguinea), two dogwoods 

 (Rhamnus frangula and catharticus, Linn.) , the box, and the black 

 whortleberry (Vaccinium uliginosum, Linn.), which have left 

 their impressions in the tuffs. The herbaceous plants are very 

 scarce; they are the great manna-grass (Glyceria spectabilis, 

 M. & K.), the reed, and the hart's-tongue fern (Scolopendrium 

 officinale). With the exception of extinct species and of the 

 box, these are all plants which now occur in Wirtemberg. Yet 

 the sycamore and the whortleberry are not found in the neigh- 

 bourhood of Cannstatt ; the sycamore grows on the mountains, 

 and the whortleberry in peat-bogs. On the whole, climatal 

 conditions are implied in the flora of Cannstatt similar to those 

 now prevalent in the same locality. Probably the tuffs of the 

 Cannstatt basin which there covered the Loess, were deposited 

 in the latter part of the Quaternary epoch at a time (after the 

 retreat of the glacier) when the climate again approximated to 

 that which is now existing. 



Of plants indicating a colder climate than we have at pre- 

 sent, only two have been discovered. In old turbaries of Ivrea, 

 and in drift debris near Mur in Styria, trunks of the Siberian 



