. Results of a biological survey of Mount Shasta, California. Natural history; Natural history. )â ] WHITE-BARK PIXE BELT. 43 tl^em descend in tongues considerably below tlie usual lower limit of tlie belt to which they belong. The most extreme case of the kind observed is on the east side of the series of hills and ridges known on the map as 'Gray Butte,' where a gulch, sheltered from the warm after- noon sun and moistened by seepage from melting snows, carries the hemlocks to a lower altitude than they reach elsewhere. On suitable slopes they usually begin about 7,200 or 7,300 feet and range
. Results of a biological survey of Mount Shasta, California. Natural history; Natural history. )â ] WHITE-BARK PIXE BELT. 43 tl^em descend in tongues considerably below tlie usual lower limit of tlie belt to which they belong. The most extreme case of the kind observed is on the east side of the series of hills and ridges known on the map as 'Gray Butte,' where a gulch, sheltered from the warm after- noon sun and moistened by seepage from melting snows, carries the hemlocks to a lower altitude than they reach elsewhere. On suitable slopes they usually begin about 7,200 or 7,300 feet and range up to about 8,000 feet. The highest altitude at which they were observed is 8,700 feet, a little east of Mud Creek Canyon, where a few stunted trees were found among the white-bark pines. Their extreme upper limit is thus a thousand feet lower than that of the white-bark pines. This is. Fig. 25.âGroup of alpine hemloclts near Deer Canyon. due, in part at least, to the character of the upper slopes, where no trees can grow except on the ridgesâas explained under the head of Timberline (pp. 27-30)âand here the ridges are too exposed and too dry for hemlocks. On Shasta the alpine hemlock does not grow in such luxuriance or attain such dimensions as in the Cascade Eange. The average height of mature trees seems to be 80 or 100 feet; the average diameter a little less than 3 feet. Trunks i and 5 feet through are by no means rare and the one shown in the accompanying j)hotograph (fig. 26) meas- ured 6 feet. It is a characteristic habit of hemlocks on sloping ground to grow in clusters, 3 to 7 springing from a common base. In this way, when young, they are better able to withstand the pressure of the Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Merriam, C. Hart (Clinton Hart), 1855-1942. Washington,
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