Palmer — Flora of the Grand Full* Chert Barren*. 101 



like masses thus detached lie isolated at the foot of the 

 cliff or well out in the stream itself, bearing mute testi- 

 mony to the slow ravages of time. The general and ex- 

 tensive fracturing of the beds, due to the brittle nature 

 of the rock, has doubtless been caused by stress and dis- 

 placement, resulting either from a general upward move- 

 ment of the region or a local settling in consequence of 

 solution of the underlying limestone. Both causes have 

 been operative at times more or less remote, and the lat- 

 ter at least is still going on to some extent. 



Where a fissure has determined the line of cleavage the 

 face of the cliff is often smooth and bare, not even a lichen 

 finding foothold on its barren surface. However, owing 

 to the peculiar gnarled and brecciated nature of the rock, 

 the cliff faces are usually very irregular, affording many 

 hollows, crevices and shelves, where soil borne by the 

 wind or transported by rainwater from the hills above 

 or by the alluvium laden waters of the stream in times 

 of flood, finds ready lodgment. Here soon a few hardy 

 mosses, grasses and other herbaceous plants establish 

 themselves, adding vegetable mold to the deposit from 

 year to year, and thus affording sustenance to other immi- 

 grants, until in time the face of the cliff is adorned with 

 a diversified flora wherever a little shade and moisture 

 exist. 



In such situations are found several ferns, some of 

 them not known elsewhere in the region. These are Dry- 

 opteris marginalis, Asplenium Trichomanes and Cheil- 

 anthes lanosa, although the last also extends up into the 

 barrens and flourishes wherever a ledge or irregularity 

 of surface affords a little protection. Asplenium par- 

 r ill u in, Woodsia obtusa and several other ferns also 

 abound, and Melica nitens and Arabis laevigata are quite 

 characteristic, with many other plants common to the 

 barrens and surrounding woods. 



Where the horizontal surface of the chert is smooth 

 and level a condition of absolute barrenness prevails. This 

 is however the case only over very small spots, as in gen- 



