GEOLOGY. 249 



Alpine flora of Europe. The woody belt of coniferous trees be- 

 gan at an average elevation of 6,000 feet. Its densest growth Avas 

 at between 7,000 and 9,000 feet elevation, and its termination was 

 at an average height of 11,300 feet. The growth was most dense 

 and varied where there was the greatest and most regular amount 

 of aqueous precipitation. At still higher elevations the actual 

 limit of tree growth was determined by conditions of temperature 

 which satisfactorily explained the peculiar features of vegetation 

 there met with. This belt of trees terminated with singular 

 abruptness. The probable explanation was that this timber line 

 marked the extreme point of minimum winter temperature below 

 which no phenogamous vegetation could exist. After alluding 

 to the meteorological conditions of the region, the paper went on 

 to point out the peculiar dwarfed tree-growth scattered occasion- 

 ally above the timber line. It was on the most open exposures 

 above that the Alpine flora was most diversified and attractive, 

 presenting from June to September a succession of colors most 

 attractive to the e3'e of the naturalist. Out of 142 species 56 were 

 exclusively confined to these Alpine exposures. The usual char- 

 acteristics of Alpine plants were a dwarfed habit of growth, late 

 period of flowering, and early seeding, the forms being exclu- 

 sively perennial. Of the 34 natural orders in the Alpine flora 31 

 belong to phenogamous plants, the remaining three were of the 

 higher order of cryptogams. Of the latter, ferns were repre- 

 sented by a single species not exclusivel}^ Alpine {Cnjptogramia 

 acrostichoides) . Mosses were more numerously represented, 

 but were still comparatively rare. Lichens were most abundant, 

 and aff'orded the greatest number of species. The superficial ex- 

 tent of these bare Alpine exposures in Colorado Territory had 

 been roughly estimated at from 1,200 to 1,500 square miles. After 

 a brief allusion to the fauna of the region, the paper stated that 

 when accessible it would doubtless afford a favorite resort for 

 summer pasturage, and eventually yield choice dairy products, 

 equalling those of the Swiss Alps, and produce delicate fibrous 

 tissues rivalling those of the looms of Cashmere. As a summer 

 resort it was unexcelled in the purity of its atmosphere, the 

 clearness of its streams, and its picturesque and extended views. 

 The paper concluded with some topographical details and with a 

 list of Alpine plants. 



ON SURFACE CHANGES IN HAINE. 



Professor N. T. True, at the meeting of the American Associa- 

 tion at Salem, read a paper " On Surface Changes in Maine, indi- 

 cating the length of time since the close of the Quaternary Pe- 

 riod." 



The paper began by stating that the almost infinity of time 

 since the earth was spoken into existence was now generally ac- 

 cepted not only by geologists, but by non-scientific men. This 

 had led some writers to give loose reins to their imagination, and 

 to attribute an immense period of time since the close of the last 



