ocr., 1899.] ROCK SLOPES. 25 
ROCK SLOPES. 
The whole upper part of the mountain between the glaciers and snow 
banks above and the forest belt below consists of bare rocky slopes, 
broken at intervals by precipitous cliffs and small heather meadows. 
The slopes are largely pumice sand, strewn and mixed with fragments of 
gray volcanic rock, among which the individual plants are so scattered 
as to disappear in the general view.! White-footed mice (Peromyscus 
gambeli) are common on these slopes, feeding on seeds of Polygonum 
newberryt and other timberline plants. Pocket gophers (Thomomys 
monticola) occur here and there and throw up their characteristic mounds 
in the pumice sand between the rocks. They subsist on the tough roots 
Fic, 12.—Characteristic rock slope on north side of Shastina. 
of alpine plants, and were observed at intervals up to an altitude 
of 9,000 feet. The pika or rock cony (Ochotona schisticeps) inhabits 
steep rock slides at distant points around the peak, and Jays up stores 
of plants for winter use. Another mammal inhabiting the rock slides 
'The commonest plants of the bare stony pumice slopes are: .{goseris monticola, 
Antennaria media, Arabis platysperma, Chenactis neradensis, Chrysothamnus bloomeri, 
Cymopterus terebinthinus, Eriogonum polypodum, L. pyrolufolium, Lrigeron compositus 
trifidus, Hulsea larseni, H, nana, Lutkea pectinata, Lupinus ‘ornatus,’ L. lyalli, Pent- 
stemon menziesi, Phlox douglasi diffusa, Polygonum newberryi, P. shastense, Saxifraga 
tolmiei, Senecio canus, Silene grayi, S. suksdorfi, Spraguea umbellata, Streptanthus 
orbiculatus, and Violu purpurea, Besides these, several ferns occur very sparingly 
on the rock slopes. These are Dryopteris uculeatu scopulina, (ystopteris fragilis, 
Cheilanthes gracillima, and Pregopteris alpestris. 
21753—No. 16-—_—_4 
