616 



SCIENCE. 



[N. S. Vol. VIII. No. 201. 



* * One of the most evident peculiarities 

 ■of such a spot as this, in southern New 

 England, is that the dense shade and abun- 

 dant evaporation maintain a temperature 

 'during the hottest summer weather that is 

 far below that of the surrounding country. 

 In these aspects of coolness, moisture and 

 shade there is a striking resemblance to 

 the woods Evotomys gapperi inhabits in 

 extreme northern New England and other 

 parts of the Canadian zone." These ac- 

 counts, interesting and suggestive as they 

 are, give no clue to the exactness of corre- 

 spondence between the temperature of the 

 southern boreal islands and that of the main 

 northern part of the boreal zone. So far 

 as I am aware, no attempt to correlate the 

 two has yet been published. 



During the summer of 1897 I had the 

 opportunity to make some approximately 

 exact observations on the relative tempera- 

 tures of a ' boreal island ' and the immedi- 

 ately contiguous upper austral zone in the 

 bottom of Fort Valley, at the north end of 

 Massanutten Mountain, Warren County, 

 Virginia. The locality was so inaccessible 

 — to reach it and return necessitated a 

 drive of nearly tM'enty miles — that only a 

 small part of the day could be spent in 

 making observations, and my instruments 

 were merely cheap thermometers bought at 

 a country store ; but, in spite of these ob- 

 stacles in the way of completeness and ac- 

 curacy, the results are sufficiently positive 

 to show how important a field is open for 

 similar work done under favorable condi- 

 tions and with accurate instruments. 



Fort Valley lies between two parallel 

 ranges of low mountains, extending nearly 

 north and south, between the forks of the 

 Shenandoah Eiver. Its eastern side is formed 

 by the abrupt, regular, western slope of Mas- 

 sanutten Mountain. On its western side the 

 slope is less precipitous, and the mountain 

 chain is much broken into separate peaks 

 and irregular ridges. At its point of open- 



ing into the broad level Shenandoah Val- 

 ley, two miles south of the railroad station 

 of Waterlick, Fort Valley is narrowed to a 

 mere pass, scarcely wide enough to allow the 

 exit of a small stream. Passage Creek, and a 

 wagon road. At this point the bottom of 

 Fort Valley is only about 750 feet above 

 sea-level, and scarcely 200 feet above the 

 nearest point on the Shenandoah River. 

 On the east Massanutten Mountain rises to 

 an elevation of some 1,800 feet, and on the 

 west Three Top Mountain barely reaches 

 2,300 feet. Just here the west slope of Mas- 

 sanutten Mountain is unusually precipi- 

 tous. For several hundred feet below the 

 summit the face of the mountain is a sheer, 

 bare clifif ; below this a rough talus slopes 

 abruptly to the edge of Passage Creek. 



The upper austral flora of the Shenandoah 

 Valley passes uninterruptedlyover these low 

 mountains and through Fort Valley. Near 

 the mouth of the Fort a few characteristic 

 species, such as the pawpaw and persimmon, 

 both of which are very common immedi- 

 ately outside, disappear, but this is evidently 

 due to lack of congenial soil, as both grow 

 at much greater heights on the neighboring 

 mountains. A fine growth of hemlock gives 

 the place a somewhat un-austral aspect, but 

 these trees are freely interspersed with gums 

 (Nyssa), three-leaved hop trees (Ptelea), 

 fringe trees ( Chionanthus) , tulip trees {lArio- 

 denclron) and southern bass woods (Tilia 

 pubescens) — a typical austral assemblage. 



The mammal fauna outside of the ' boreal 

 islands ' showed no peculiarities. It was 

 simply that of the upper austral zone, 

 and it extended wherever I trapped on the 

 mountains as well as in the valleys. Among 

 the hills on the west side of Fort Valley are 

 a few small cold streams, and on the banks 

 of these I secui-ed two boreal mammals, a 

 red -backed mouse {Evotomys carolinensis) 

 and a shrew {Sorex fumeus). The nearest 

 points from which the former has been re- 

 corded are Eoan Mountain, North Caro- 



