NATURAL AREAS AND REGIONS 



557 



1. UTAH 

 BY C. F. KORSTIAN 



Utah is situated near the center of the 

 western United States on the great 

 Inter-mountain Plateau. The main Wa- 

 satch Mountain Range extends north 

 and south practically the entire length 

 of the state ; while the Uinta Mountains 

 extend eastward from the Wasatch 

 Range paralleling the Wyoming state 

 line. By far the greater part of the 

 state lies above an elevation of 4000 ft. 

 The main summits of the mountains 

 attain altitudes of 10,000 to 13,000 ft. 

 A number of isolated mountain masses 

 occur in practically every part of the 

 state. Situated, as it is, in the interior 

 of the continent and to the leeward 

 of the great Sierra Nevada Mountain 

 Range all of the state, with the exception 

 of the higher mountains, has a distinctly 

 arid climate. The annual rainfall varies 

 from 5 to 15 in. throughout the lower- 

 lying portions, while on the mountains 

 the precipitation is 20 to 30 in. per year. 



All the country west of the summit 

 of the Wasatch Range drains into the 

 Great Basin. The largest body of water 

 in the state is the Great Salt Lake, 

 the water of which is so salty that a small 

 shrimp is practically the only form of 

 life found in it. This lake is the present 

 day remnant of the ancient Lake Bonne- 

 ville which formerly occupied an 

 extremely large area in this region. 

 The old shore-line may be traced along 

 the western foothills of the Wasatch 

 Range all the way from Provo to a point 

 some 30 mi. north of Ogden. 



Practically all of the valleys and the 

 plateau country between the mountain 

 ranges were originally a sagebrush 

 desert, the dominant species being 

 sagebrush (Artemisia tridentata) asso- 

 ciated with other small-leafed shrubs. 

 Greasewood (Sarcobatus vermiculatus), 

 andshadscale (Atriplexsp.} are the domi- 

 nant species on extensive areas of alkali 

 flats in the arid valleys. A distinctly 

 halophytic association of vegetation is 

 found on the salt flats adjacent to the 



Great Salt Lake. On the coarser soils 

 of the foothills the junipers (Juniperus 

 utahensis and /. monosperma) and, 

 in the southern part of the state, pinyon 

 (Pinus edulis) form open park-like wood- 

 lands. (The foregoing types of vegeta- 

 tion fall within the Upper Sonoran 

 Life Zone.) 



A small area of extreme desert con- 

 ditions occurs along the Virgin River 

 in southwestern Utah. This is char- 

 acterized as a small-leafed shrub desert 

 in which the creosote bush (Covillea 

 tridentata) is the dominant species 

 (Lower Sonoran Life Zone). While no 

 mammals except small burrowing forms 

 occur naturally in this area, reptiles 

 are very abundant. 



The mountains were originally clothed 

 with a coniferous forest which is often 

 regarded as a southward extension of 

 the northern evergreen forest. In the 

 southern part of the state western 

 yellow pine (Pinus ponderosa scopulo- 

 rum) is most abundant. In the central 

 and northern part of the state this 

 species is largely replaced by a brush 

 cover composed of various species of 

 shrubs and small trees (Transition Life 

 Zone). The next higher type altitudi- 

 nally is that in which Douglas fir (Pseu- 

 dotsuga taxifolia) and white fir (Abies 

 concolor) are dominant (Canadian Life 

 Zone). In the Uinta Mountains lodge- 

 pole pine (Pinus contorta) also forms 

 rather extensive stands. On the higher 

 mountains above 9000 ft. Engelmann 

 spruce (Picea engelmanni) and alpine 

 fir (Abies lasiocarpa) are the char- 

 acteristic species (Hudsonian Life Zone). 

 The forest conditions are described 

 more fully by Baker and Locke in con- 

 nection with the discussion of the 

 National Forests in the Intermountain 

 Region. 1 Succulent plants are confined 

 principally to the higher mountain 

 slopes. 



The following animals have been 

 reported as inhabiting the sagebrush 

 desert: pronghorn antelope (Antilo- 

 capra americana) , coyote (Cam's spp.), 



1 This volume, page 224. 



