438 BOTANICAL GAZETTE [November 



white oak stumps 4 feet and 5 . 5 feet in diameter indicate that the 

 region was allowed to pass at least through the oak succession, and 

 chestnut 2 feet in diameter with hard maple 1 inch in diameter show 

 that it is the day of the chestnut with the promise of hard maple 

 later. Old landmarks of hard maple and chestnut give evidence of 

 a previous attainment of that stage of succession, which appears to 

 be the temporary climax of the east and south slopes. 



TRAP CLIFF 



I 



The cliff is of greater height on the west side of Mount Tom than 

 on the north side of Mount Holyoke. The numerous faults on 

 Mount Holyoke run at right angles to the range, and the more active 

 erosion along the fault lines increases the amount of talus. This, 

 in addition to the glacial drift deposited on the north side, accounts 

 for the talus reaching the top of the mountain and burying the 

 cliff face, except for short spaces between the fault lines. On 

 Mount Tom the faults are fewer and run parallel with the cliff face, 

 and the glacier left no deposit except at the Nonotuck end (see map)- 



A lichen flora, yet undetermined, is established on most of the 

 cliff, Umbilicaria playing a conspicuous part. The rock flakes off 

 so rapidly that it is doubtful if any later vegetation is established. 

 Often before the lichens are established the rock flakes off and is 

 added to the talus below. The talus is made up of large flakes 

 with or without lichens upon them. 



The crevices and shelves afford a more permanent foothold and 

 conifers have become established here, so that from a distance the 

 mountain side appears to be rather well covered with trees. 



The following species are found in crevices, and on shelves of 

 the east-facing cliff: Spermatophyta: Trees. — Juniperus virginiana, 

 Pinus Strobus, Pinus resinosa, Tsuga canadensis. Herbs. — Saxi- 

 fraga virginiensis, Corydalis sempervirens, Campanula rotundifolia. 



Pteridophyta: 

 phyta: Hedwi 



pi 



B ryo- 



pocarp 



the 



successions. The first stages in the group of initial succes- 



same 



tages are different. The many shelves found on the east side offer 



