OCT., 1899.] 



ROCK SLOPES. 



25 



KOCK SLOPES. 



The whole upper part of tlie inouiitaiii botween the glaciers aud snow 

 banks above and the forest belt below consists of bare rocky slopes, 

 broken at intervals by i)recipitons 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 {Peroniyscns 

 (jamheli) are common on these slopes, feeding on seeds of Polygonum 

 neicherryi and other timberline plants. Pocket gophers [Thomomijs 

 iuonfi col a) ocaur here and there and throw up their characteristic mounds 

 in the i)umice sand between the rocks. They subsist on the tough roots 









Fig. 12. — Chara<teristic rook slope on noitli .side of .Sljastiua. 



of alpine plants, and were observed at intervals up to an altitude 

 of 9,000 feet. The pika or rock cony (Ochotona schist icep.s) inhabits 

 steep rock slides at distant points around the peak, and lays up stores 

 of plants for winter use. Another mammal inhabiting the rock slides 



' Tlie commonest plants of the bare stony pumice slopes are: A<ioser'is moiiiicola, 

 Antennaria media, Arah'in lylatuspcrma, Clia'nacfis neradensis, Chri/aothamiiiis hloomeri, 

 Cjjviopterus Urehinihinns, Eriogonum pohipodum, E. pyrohi folium, Erigeron compositus 

 irifidus, Hulsea larseni, II. nana, Luilcea pectinata, Lupintis ' ornatus,' L. Jyalli, I'ent- 

 siemon memiesi. Phlox domjlasi diffusa, Polygonum netvherryi, P. shasiense, Saxifraga 

 tolniiei, Senecio canus, Silene grayi, S. sulcsdorji, Spraguea umhellata, Streptatiiliua 

 orhiculatus, and Viola purpurea. liesidt-s these, several ferns occur very sparingly 

 on the rock slopes. These are Dryopttrls acnlcata aropinina, Cyxtoptcris fnignis, 

 Clieilanthen graciUima, and Pricgoptcris alpe><tris. 



21753— No. 16 4 



