Blue Mountain Ecological Province

 

 

 
 
 

Location

In Oregon, this province constitutes the mountainous northeastern segment of the state. It covers slightly less than 6 million acres and includes all of Wallowa County, major segments of Union, Umatilla, Baker, Grant, and Morrow counties, and small segments of Wheeler and Gilliam counties. The old mill town of Kinzua in northwestern Wheeler County is in the westernmost tip of Blue Mountain Province. The province extends north into Washington and east into Idaho.

 

 
 

Description

The Blue Mountain Province in Oregon is typified by groups of rugged mountains, steep canyons, and extensive plateaus divided by dendritic-pattern drainages (Fig. 3). Basalt is the major bedrock underlying mountains and plateaus, which accounts for the typical rimrock canyons. The most rugged mountains in the province are the Eagle Mountains in the area where Wallowa, Union, and Baker counties join; the Elkhorn Mountains in western Baker and northeastern Grant counties; and the Strawberry Mountain area in central Grant County. These mountains consist of uplifted granitic, basaltic, and various metamorphosed shales, sandstones, limestones, greenstones, and tuffs. 9

Figure 3: Rugged basaltic foothills of Blue Mountain Province, Oregon

The Wallowa Valley from Wallowa to Joseph and the Grand Ronde Valley from Union to LaGrande and Elgin are used for irrigated agriculture and for some dryland farming. South of Pilot Rock and east of Pendleton, some footslopes of Blue Mountains are dryland farmed to produce mainly wheat and barley. Most of the province is timbered and natural grasslands (Fig. 4).

Figure 4: Typical view of Blue Mountain Province, showing interspersed natural grasslands and forested areas

Elevation within Blue Mountain Province in Oregon is mainly between 3,000 and 5,000 feet. The lowest point is below 1,000 feet where Oregon, Washington, and Idaho join on the Snake River; i.e., at the extreme northeast corner of Oregon and the extreme southeast corner of Washington. The highest peaks in the Eagle Mountains are Sacajawea Peak at 9,839 feet, Matterhorn at 9,832 feet, and Aneroid Peak, Petes Peak, Twin Peaks, and Point Joseph which are all above 9,600 feet. In the Elkhorn Mountains, Rock Creek Mountain is 9,106 feet, Elkhorn is 8,931 feet, Twin Peaks is 8,897 feet and Mt. Ireland is 8,321 feet. In the Strawberry group, Strawberry Mountain is 9,038 feet, Slide Mountain is 8,521 feet, Canyon Mountain is 8,007 feet, Indian Creek Butte is 7,889 feet, and Pine Creek Mountain is 7,390 feet. These elevations are according to U.S. Forest Service maps.

 

 
 

Soils

Soils of the Blue Mountain Province can be conveniently grouped according to the natural vegetation produced: upland grasslands, upland shrub–grasslands, meadows, forested areas, subalpine, and alpine.

Upland soils that produce natural grasslands (i.e., less than 10% natural shrub cover) are quite uniform in characteristics throughout the province. These soils have been formed primarily in silty aeolian deposits that reportedly originated and were blown south during the era of receding glaciers farther north in Washington. Subsequent aeolian deposits of volcanic ash during eruptions, such as from Mazama, have occurred to influence the parent materials in which these soils were formed.

Where these soils occur on plateaus and north-facing slopes under climatic conditions associated with mountainous topography—usually about 3,500 to 4,000 feet elevation and receiving about 15 inches or more annual precipitation—they generally are moderately deep to shallow, have very dark brown to black fairly thick silt-loam-texture surface layers, and dark brown moderately fine to clayey subsoils over basalt bedrock. Grassland soils on north-facing slopes are normally deeper than those on plateaus. This is probably due to the snow-drift effect of prevailing southerly winds that have redistributed aeolian deposits. Soils on south- and west-facing slopes in canyons and mountainous terrain at these elevations have dark brown medium-texture surface layers and moderately fine-texture subsoils. They are usually extremely stony and fairly shallow over basalt bedrock.

Upland soils that produce natural shrub–grassland vegetation (i.e., 10% or more natural shrub cover) occur mainly in two situations in Blue Mountain Province. The most common is locally called scabland. These soils, which occur on plateaus and ridgetops, are very shallow and very stony. They have thin loamy surface layers and clayey subsoils and are usually less than 10 inches deep to basalt bedrock. Normally, they frost heave severely and are very susceptible to sheet erosion.

The other upland soils that produce natural shrub–grassland vegetation occur on very steep north-facing areas within the elevation range of natural grasslands. These areas represent snowdrift pockets that receive moisture beyond that from normal precipitation. The north-facing aspect also increases effectiveness of the moisture received. These soils are moderately deep to very deep and usually not stony. They have thick black silty surface layers and brown silty to clayey subsoils. Outcrops of bedrock may exist.

Throughout the natural grasslands of Blue Mountain Province, grassland soils on some plateaus and ridges commonly occur in a unique land pattern locally called biscuit scabland. This pattern consists of small mounds of grassland soils 5 to 20 or more feet in diameter and usually about 20 to 36 inches deep over basalt bedrock. Each of these mounds, or biscuits, is surrounded by very shallow, very stony shrub–grassland soils over basalt bedrock, which are locally called scabland. Hence the name, biscuit scabland. The biscuits vary in shape, usually round but sometimes oblong. They occupy from about 5 to 30% of the area in which they occur. Some spectacular biscuits are in the vicinity of Flora in north-central Wallowa County; they are 5 feet high or more. Also in that vicinity are biscuits on which ponderosa pine grows.

For explanation of the origin of this particular land pattern, refer to the description of Oregon’s Columbia Basin Ecological Province in which biscuit scabland is a prominent, widespread phenomenon.

Soils on meadows vary from locality to locality because they are formed in alluvium from adjacent watersheds and are directly related to the degree and longevity of wetness, which varies from sometimes dry to always wet.

Soils along major streams usually have medium- or loamy-texture surface layers and gravelly substrata. Gravelly surface layers and gravel bars are common. Woody vegetation is able to flourish on these kinds of meadows partly because water flowing through the soil profile is aerated. In contrast, meadow soils in swales and along minor meandering waterways usually have medium-texture surface layers and clayey substrata. These soils seldom produce native shrubby species, except for certain species of willow, because water in the soil is ponded and not aerated.

Some soils on mountain meadows in Blue Mountain Province have prominent, sometimes thick layers of volcanic ash in the profile that likely washed off surrounding watersheds. These ashy soils erode like “sugar” when disturbed or exposed and form vertical, sometimes deep channels which are very difficult to rehabilitate because of the erosiveness of the ash layers.

Soils of dry meadows generally have medium-texture surface layers and clayey subsoils. These soils occur as small basins within the forested area, as areas around the perimeters of wet meadows, and as shoestring bottoms along intermittent streams, They are moderately deep and usually not stony.

Soils in prominent valleys generally are a mixture of alluvium and low-terrace materials; the mixture varies from location to location within a valley. In the vicinity of Hot Lake in Grande Ronde Valley, the soils are poorly drained and affected by sodium; they are known as black alkali. This is probably the only occurrence of sodic soils in Blue Mountain Province.

Soils of forested areas in Blue Mountain Province vary according to the type of forest. Stands of ponderosa pine with an understory of bunchgrasses usually occur on plateaus, ridgetops, and south-facing slopes. These soils have loamy surface layers and clayey subsoils over basalt bedrock. They are usually shallow, stony, susceptible to erosion, and, when severely eroded, they frost heave. This forms a stone pavement on the surface which seriously hinders natural revegetation and increases water loss from the watershed through runoff.

Several different combinations of soils, moisture, aspect, and slope are related to mixed ponderosa pine–Douglas-fir stands that have an understory of pinegrass, elk sedge, and associated species.

• In areas receiving about 26 to 40 inches precipitation on shallow-soil south exposures. These soils have loamy surface layers and clayey subsoils and are usually stony.

• In areas receiving about 16 to 26 inches precipitation on moderately deep to deep soils that are nearly level or slope slightly north or south. These soils have loamy or ashy surface layers and moderately fine to clayey subsoils. They may be stony.

• On steep, north-facing slopes of drainages below the main forested zone. These soils generally are moderately deep and stony with loamy or ashy surface layers and loamy to moderately fine-texture subsoils.

Soils of the grand fir–Douglas-fir and grand fir–alpine fir forests generally are moderately deep to very deep with thick ashy upper layers and loamy to clayey subsoils. These soils occur on moderately steep to steep north-facing slopes and, above about 6,000 feet where precipitation exceeds about 40 inches, these soils occur on gently sloping to rolling topography.

Soils of the subalpine fir–whitebark pine and of alpine nonforested areas generally are very gravelly, stony, or rocky and very shallow to moderately deep. In the Blue Mountain Province they occur mainly at about 7,000 feet elevation. Essentially, these soils are primarily raw materials from the wide variety of parent materials forming the mountains.

 

 
 

Climate

Based on data from 14 official weather stations, which represent a cross-section of the province, the average annual precipitation for the province is about 22.4 inches. About 32% of annual precipitation falls during April through July, the herbaceous native-plant growing season. November through March precipitation is about 54% of the annual total. Average January maximum and minimum temperatures are 33.8 and 15.1°F, respectively. Average April through July maximum and minimum temperatures are 70.2 and 38°F, respectively.

Precipitation and temperature data vary by locality (Table 1).

A recent precipitation map53 shows about 115 inches annual precipitation in the Eagle Mountains south of Enterprise, over 45 inches in the Elkhorn Mountains west of Baker City, and over 35 inches in the Strawberry Mountain group southeast of John Day. The most arid portion of the Blue Mountain Province is in the lower reaches of the Imnaha and Snake River canyons, which is also the lowest elevation in the province.

 

 

 

 
 

Vegetation

According to the 1936 State of Oregon Forest Type Map,54 which predates extensive logging, about one-third of the entire Blue Mountain Province was at that time primarily natural grasslands; about two-thirds was forested.

Natural grasslands (i.e., less than 10% natural shrub cover) occur sporadically throughout lower elevations of the Blue Mountain Province. They range in size from small openings and long narrow ridgetops in forested areas to extensive open grasslands. They extend along the entire northern province boundary from near Pilot Rock west to near Kinzua; in the vicinity of Ukiah, Starkey, LaGrande, and Elgin; and in central and northern Wallowa County from Wallowa–Enterprise–Joseph east and north past Findley Buttes and Zumwalt, including the breaks of the Snake, Imnaha, and Grande Ronde canyons. The grasslands near Findley Buttes are the highest native-forage-producing upland sites in eastern Oregon when in vigorous, high-ecological status. They probably are a model of what has been called the Palouse Prairie (Fig. 5).

Figure 5: Managed natural grasslands in Blue Mountain Province, Oregon

Essentially the same combination of plant communities and soil series occurs throughout these widely separated grasslands. This is due to the province-wide uniformity of soil parent materials and climatic conditions under which these soils and plant communities were formed.

On these natural grassland ecological sites, the basic perennial grasses are Idaho fescue, bluebunch wheatgrass, Sandberg bluegrass, and prairie junegrass. Big bluegrass, pinegrass, elk sedge, and timothy occur on more moist upland sites. Dry meadows produce a wide variety of species including Idaho fescue, sod bluegrasses, slender wheatgrass, thin bentgrass, California oatgrass, Columbia needlegrass, and threadleaf sedge. Wet meadows are typified by tufted hairgrass, redtop, slender wheatgrass, sod bluegrasses, baltic rush, Nebraska sedge, and red fescue.

Uniquely, in the lower reaches of the Snake and Imnaha canyons, which is the most arid portion of this province, there are small areas containing Fendlers threeawn. This is probably the only location in Oregon where it grows. Its major range is in the Great Plains. The oldtimer local ranchers called it “democrat” grass and claimed it did not show up until Franklin D. Roosevelt and the Democrats came into political power in the 1930s. Peck’s 1961 manual of higher plants of Oregon 23 cites it as being in these canyons. It is possible that the ranchers, having wintered livestock in the canyons for years, first noticed this grass when the severe drought of the 1930s diminished other forage species; coupled with intense winter grazing, this made the previously unnoticed threeawn appear prominent because it is apparently unpalatable when mature. How the species got there in the first place could be the basis for a campfire storytelling session: Nez Percé Indians returning from buffalo hunts in Montana? Explorer Frémont’s expedition was once lost in the Imnaha canyon?

Blue Mountain Province natural grassland sites are characterized by an abundance and wide variety of perennial forb species which make up 10 to 15% of natural plant communities on most sites.

Several low shrubs, such as low Oregon grape, wax currant, rose, common snowberry, green and gray rabbitbrushes, and herbaceous sage commonly occur in trace amounts in these natural grasslands. One distinctive feature of Blue Mountain Province is the overall scarcity of big sagebrush and other tall shrubs that dominate much rangeland in Oregon. Even on grasslands in deteriorated ecological status, shrubs do not become prominent in Blue Mountain Province. Rather, deteriorated grasslands are characterized by a dominance of perennial forbs, such as yarrow, gumweed, lupine, and biscuitroot and annual forbs and grasses. However, at least four species of the genus Artemisia occur in the province: big and stiff sagebrushes, tarragon, and lobed wormwood.

Along the line of demarcation between Blue Mountain and John Day provinces, both big sagebrush and western juniper, strongly characteristic of John Day Province, occur within the band or area where the two provinces join. This band of integrated vegetation is likely natural. However, it is also likely that characteristic John Day Province vegetation such as sagebrush and juniper have expanded into Blue Mountain Province due to severe grazing and timber harvest which degraded the vigor of original Blue Mountain plant communities, thereby allowing encroachment of John Day woody species. Expansion of Blue Mountain vegetation south into the John Day Province is not likely because the climate becomes abruptly more arid on the John Day side of the line. Ecological invasion more often occurs from arid to more moist situations.

Three major kinds of natural shrub–grassland (i.e., 10% or more natural shrub cover) occur in Blue Mountain Province. The most common is the site locally called scabland. The vegetation on this very shallow, very stony site is dominated by Sandberg bluegrass. Bluebunch wheatgrass, Idaho fescue, and a few other perennial grass species occur sparsely between the surface stones. Perennial forbs, such as Hooker balsamroot, biscuitroot, big-head clover, bitterroot, onion, and snow buckwheat are prominent. Stiff sagebrush is the dominant shrub; however, an occasional rose or common snowberry may occur.

An entirely different kind of natural shrub–grassland occurs on very steep north-facing areas within the elevation range of natural grasslands. These areas represent snowdrift pockets which receive moisture beyond normal precipitation. The vegetation is dominated by shrubs such as common snowberry, rose, chokecherry, hawthorn, mockorange, and ninebark. An occasional ponderosa pine or Douglas-fir may occur. The understory is dominated by Idaho fescue along with such grasses as timothy, oniongrass, Kentucky bluegrass, Columbia needlegrass, pinegrass, mountain brome, bluebunch wheatgrass, and an abundance of perennial forb species.

Bottomlands along major streams, where soils are usually gravelly, produce woody vegetation along with meadow vegetation. Water flowing through the gravelly soils is aerated, and woody species such as cottonwoods, some willow species, alder, birch, and ponderosa pine are capable of flourishing in spite of seasonal or periodic high-water tables or overflow. The understory vegetation varies widely according to the frequency and duration of soil water; the plant communities range from dry meadow to wet meadow species, usually occurring in patches.

Coniferous forest occupies most of Blue Mountain Province. These forests represent five generalized plant communities (with transition from warm to cool to cold forest), each with management implications.

1. Ponderosa pine with understory dominated by Idaho fescue, bluebunch wheatgrass, many forb species, and shrub species with pine reproduction. A warm forest.

2. Ponderosa pine with understory dominated by pinegrass, elk sedge, Idaho fescue, bluebunch wheatgrass, many forb species, and many shrub species with pine reproduction.

3. Mixed ponderosa pine, Douglas-fir, some grand fir and some larch with an understory consisting of pinegrass, elk sedge, Idaho fescue, other shade-tolerant grass and forb species, and many shrub species with pine and Douglas-fir reproduction. A cool forest. (Fig. 6).

Figure 6: Typical pine-fir-pinegrass forest in Blue Mountain Province, Oregon

4. Mixed grand fir, Douglas-fir, larch, lodgepole pine, and Engelmann spruce with sparse understory of shade-tolerant grass and forb species mainly in openings, shade-tolerant shrubs, and much grand fir and Douglas-fir reproduction.

5. Subalpine fir, larch, lodgepole pine, and Engelmann spruce with a sparse understory of shade- tolerant forbs and shrubs. A cold forest.

Subalpine areas consist of a variety of plant communities which contain species such as whitebark pine; subalpine fir; elk, Ross, and Hood sedges; green and Idaho fescues; yarrow; fleeceflower; and mountain big sagebrush. These are not coniferous forests. Rather, they are patchy patterns of various plant communities (Fig. 7).

Figure ;7: Looking south from Hawkins Pass, which is the source of South Fork Imnaha River in Blue Mountain Province, Oregon

The different kinds of soils that help differentiate Blue Mountain Province from John Day Province are supported by significant differences in the site-specific plant communities. For example, the ponderosa pine–bunchgrass ecological site occurs in both provinces and, based on casual observation, they resemble each other: pine trees, shrubs, grasses, forbs. However, numerous samples of this ecological site in both provinces reveal significant differences in the species that constitute the plant community of the site. In Blue Mountain Province, the following species regularly occur but are rarely, if ever, found on this site in John Day Province: Kentucky bluegrass, onespike oatgrass, threadleaf sedge, huckleberry, mockorange, and herbaceous sage. On the other hand, the following species regularly occur on this site in John Day Province but are rarely, if ever, found on this site in Blue Mountain Province: Wheeler bluegrass, Thurber needlegrass, Ross sedge, mountain snowberry, curlleaf mountain-mahogany, green rabbitbrush, big sagebrush, and western juniper. Obviously, these differences are not readily apparent within the belt of demarcation between these provinces but are apparent in provincewide data.

Even greater differences occur on the ponderosa pine–sedge ecological site in each of the provinces. The following species regularly occur in Blue Mountain Province but rarely, if ever, are found on this site in John Day Province: slender wheatgrass, timber oatgrass, western fescue, Columbia needlegrass, threadleaf sedge, blue wildrye, slender hairgrass, deerbrush, elderberry, spirea, ninebark, huckleberry, serviceberry, dogbane, syringa, chokecherry, bitter cherry, oceanspray, bearberry, and herbaceous sage. The following species regularly occur on this site in John Day Province but rarely, if ever, on this site in Blue Mountain Province: basin wildrye, Wheeler bluegrass, mountain snowberry, curlleaf mountain mahogany, green rabbitbrush, big sagebrush, and western juniper.

Generally, Blue Mountain Province forested-site plant communities consist of more numerous species than those in John Day Province. This is especially noticeable in the shrub component. The reason might relate to the soils and climate of Blue Mountain Province as compared to those of John Day Province.

A study of the geographic distribution of major plant species within Oregon, based on their occurrence within specific ecological provinces and on specific ecological sites, would be a worthwhile contribution to coming generations of resource scientists and managers who are increasingly required to set goals and objectives for various ecological situations.

 

 
 

Management Implications

Blue Mountain Province includes irrigated agriculture primarily in the vicinity of LaGrande, Elgin, and Enterprise which produces specialized crops, such as seed potatoes, turfgrass seed, grains, and animal forages. There is a small amount of dryland farming for grain, along with irrigated areas, between Pilot Rock and Cayuse on the Umatilla River. Some previously dry-farmed areas were put into perennial cover under the Conservation Reserve Program of the 1980s.

Most grasslands in Blue Mountain Province are privately owned, but grazing on much of these lands is closely interrelated with grazing on public lands. Public forested lands provide a high proportion of summer grazing for livestock, elk, deer, and provide summer habitat for much of the province’s wild mammals, whereas the winter ranges for livestock and most wildlife are lower elevation private lands or BLM public lands.

The ashy Tolo soil series is probably the most productive forest soil in eastern Oregon, and the Waha and Wahala series are probably the most productive upland range soils in eastern Oregon.

A very large proportion of the province is rangeland and forested. A high proportion of the forested land is publicly owned and managed under the Wallowa-Whitman, Umatilla, and Malheur national forests. A small proportion of BLM-administered public land lies along the eastern fringe of the province.

The North Fork John Day Wilderness, Hells Canyon National Recreation Area, Hells Canyon Wilderness, Eagle Cap Wilderness, Strawberry Mountain Wilderness, most of Monument Rock Wilderness, and most of the Umatilla Indian Reservation are in Blue Mountain Province. Collectively, this is a huge set-aside area requiring stringent integrated resource management.

Blue Mountain Province essentially is the entire source of water upon which all life in northeastern Oregon—and farther—depends. It is composed of a myriad of subwatersheds that capture, store, and release water into numerous drainages. This fact must be given prime consideration in all management strategies, small or large.

Resource issues, problems, opportunities, and options usually involve multiple ownerships, resources, and resource uses within Blue Mountain Province as well as with adjacent provinces. The result of what happens in Blue Mountain watersheds is far-reaching.

 

 
 

Province Demarcation

Blue Mountain and Snake River Demarcation

The line of demarcation between Blue Mountain and Snake River provinces begins in the Snake River canyon at Copperfield on the Oxbow where Snake River exits the Snake River Province and enters the Blue Mountain Province in the upper Hells Canyon. From that point, the line runs southwest up the ridge between Pine Creek and Snake River. All drainage into Pine Valley and Pine Creek is considered to be in Blue Mountain Province; however, the nearby deep Snake River canyon makes this line a matter of judgment based mainly on native plant communities and soils. From the divide on Highway 86 between Eagle Valley and Pine Valley, the line runs westerly at about 4,000 feet elevation along the upper edge of the ancient terraces south of Sparta, which is in Blue Mountain Province.

The line crosses into Union County east of Pondosa at about 4,000 feet elevation and continues northwesterly through Telocaset and around the north and west edges of North Powder Valley, then south at about 4,000 feet elevation to just west of Baker City. The ancient lake terraces, which typify the Snake River Province, are fairly apparent around the north and west sides of North Powder Valley where they butt into the basaltic mountainous uplands to the west, which typify Blue Mountain Province. West of Baker City is an apparent geological uplift that abruptly elevates the line between terraces and mountainous uplands to about 5,000 feet elevation.

The demarcation line continues south from that point west of Baker City at about 5,000 feet elevation and then west along the north side of Sumpter Valley to Sumpter and south along the west side of Sumpter Valley. Sumpter is right at the edge of Snake River Province. From Sumpter Valley, the line continues southwest at about 5,000 feet elevation around the north side of Whitney Valley in upper North Fork Burnt River. About 5 miles northwest of Whitney on Camp Creek, the line of demarcation abruptly drops back to about 4,000 feet elevation where it continues around the west side of Whitney Valley and south along the North Fork, up the Middle Fork, then south and up the South Fork Burnt River southwest of Unity.

Some segments of the line described above have stands of coniferous trees, mainly ponderosa pine, on both sides, i.e., in both provinces. However, the conifer stands in Snake River Province are growing on deep soils related to ancient Snake River terraces; tree stands in Blue Mountain Province are growing on primarily aeolian soils overlying basalt formations which typifies the Blue Mountain Province. Based solely on the presence of pines, this line of demarcation may seem insignificant. However, differences in growth indices of pine might prove to be significant and should be compared. Based on the total plant community—understory vegetation and associated trees—this major soils line is definitely significant from an ecological standpoint, which is the basis for the ecological province concept.

In the head of South Fork Burnt River about 8 miles southwest of Unity at about 4,500 feet elevation, the line of demarcation between Blue Mountain and Snake River provinces continues south and rises up to the vicinity of Table Rock at 7,873 feet elevation. This appears to be caused by a huge geologic uplift, the eastern edge of which appears to be the Table Rock–Bullrun Rock–Lone Rock escarpment of the uplifted plateau. The very rough country to the east of this uplift lies in Snake River Province. Southwest of Lone Rock, the line of demarcation returns to about 5,000 feet elevation where it remains as it continues south and around the upper North Fork Malheur River.

Near where Crane Creek joins North Fork Malheur River, the Blue Mountain Province line goes west and around the south side of Crane Prairie at about 5,000 feet elevation. It is near the junction of Crane Creek and North Fork Malheur River that the Blue Mountain, Snake River, and John Day provinces join.

Blue Mountain and John Day Demarcation

From this junction, the line of demarcation between Blue Mountain and John Day provinces continues northwesterly from south of Crane Prairie in southeastern Grant County at about 5,500 feet elevation, which places it between Summit Prairie, in Blue Mountain Province, and Logan Valley which is in John Day Province. The line follows the rims southwest of High Lake around the south slopes of Strawberry Mountain, Indian Creek Butte, and Pine Creek Mountain at about 5,500 feet elevation, and then west and north along the western slopes of Canyon Mountain. Along the north-facing slopes of Canyon Mountain, Baldy Mountain, and Strawberry Mountain (all in Blue Mountain Province), the line falls at about 4,500 to 5,000 feet or lower, based on the elevation at which volcanic ash is prominent in soils on these north-facing slopes. The volcanic ash soils typify Blue Mountain Province.

The line crosses the Middle Fork John Day River about 6 miles upstream from Bates, at about 4,500 feet elevation. Bates is in John Day Province as is the entire downstream reach of the Middle Fork. It is at this point above Bates that the Blue Mountain Province is only about 5 miles wide, from John Day Province on the west to Snake River Province on the east. This narrow area of Blue Mountain Province straddles the divide between Middle Fork John Day River and the West Fork and Middle Fork Burnt River.

The demarcation line runs northwesterly from Bates at about 4,500 feet elevation in the upper slopes of Middle Fork John Day River drainage. The old mining town of Susanville is in John Day Province. From Susanville, the line continues north at about 4,500 feet elevation, approximately the level at which truncated or exposed tuffaceous deposits form steep slopes or escarpments. These tuffaceous deposits and underlying clayey materials typify the John Day Province.

From just west of Putney Mountain, in Blue Mountain Province, the line continues west and crosses Highway 395 near Meadow Brook Summit south of Dale at about 4,000 feet elevation. From there the line meanders generally northwest at about 4,000 feet elevation then pitches abruptly down a ridgetop to cross the North Fork John Day River at the first oxbow that changes the river’s flow from west to south. This is about 18 miles downriver from Dale Bridge.

From west of Putney Mountain to the point that the line of demarcation crosses the North Fork John Day River, all watersheds draining north into the North Fork are in Blue Mountain Province. These include Desolation Creek, Meadow Brook Creek, and the steep north-facing timbered slopes along the North Fork. The soils in these watersheds are medium-texture. Usually they have ashy surface layers formed by aeolian deposits of volcanic ash that accumulated on the north-facing slopes like snowdrifts. Underlying materials are generally basaltic. Ashy surface soils and basaltic underlying materials typify much of the Blue Mountain Province, especially in timbered areas, and the timber exists because of these soils, not vice versa.

From the oxbow of the North Fork John Day River where the line of demarcation crosses, the line follows the river east upstream to about a half mile west of the confluence of Deerhorn Creek with North Fork. At this point, the line rises north out of the John Day canyon along the ridge west of Deerhorn Creek to about 4,000 to 4,500 feet elevation. From there it meanders westerly in and out of tributary canyons as it follows the major upper-level rimrocks at the south edge of the plateau. Plateau areas to the north of this line are in Blue Mountain Province, and the canyon slopes of North Fork and tributaries below about 4,000 feet elevation are in John Day Province.

Placing the line of demarcation up the ridge west of Deerhorn Creek was a judgment call. It was deemed that the Deerhorn and Camas creeks’ drainages resemble the upstream Blue Mountain Province soils and vegetation more than they resemble the downstream John Day Province soils and vegetation.

Buckaroo Flat, Thompson Flat, Potato Hill, Grassy Butte, and other such plateau points above about 4,000 feet elevation that jut out into the John Day River drainage are in Blue Mountain Province. There is evidence that this junction actually may be a belt, rather than a line, which is common where ecological provinces or ecological sites join. For example, at Thompson Flat at the south end of Potamus Ridge is an area of biscuit scabland (patterned ground) in which the soil of a biscuit was 0 to 6 inches silt loam, 6 to 10 inches silty clay loam (these are typical surface soil textures in Blue Mountain Province), 10 to 20 inches silty clay, and 20 to 30 inches or more clay (these are typical subsoil characteristics in John Day Province). In this biscuit scabland site, the interspersed scabland soil is very shallow and very stony with abundant surface basaltic stones, which is typical for scabland in both Blue Mountain and John Day provinces.

Geologists have reported that the Blue Mountains of Oregon were at one time the north shore of an ancient sea. If so, clay deposits such as at Thompson Flat, at about 4,000 feet elevation, are likely associated with ancient lake terraces. It is interesting to note, as supporting evidence, that the ancient lakeshore terraces signifying where Snake River Province joins Blue Mountain Province in Baker County are very visible at 4,000 feet elevation near Keating and Richland. The continuity of the 4,000 feet elevation level, coupled with evidence of ancient lakebed terraces, obviously has great significance from an ecological province perspective.

Kinzua is in westernmost Blue Mountain Province. South and west of Kinzua the line of demarcation between Blue Mountain and John Day provinces is about 4,000 feet elevation. This area has a mixture of forested soils that typify the Blue Mountain Province and other forested soils that typify John Day Province. This pattern of soils creates a belt of demarcation 2 to 3 miles wide. Consequently, a mapped line, such as the 4,000 feet elevation, is judgmental yet consistent with the line of demarcation southeast of Kinzua. The major difference in these soils is that those typifying Blue Mountain Province have medium- or moderately fine-texture profiles and are usually atop basalt bedrock; soils typifying John Day Province have clayey or clay subsoils and are atop ancient fine-texture sediments or tuffaceous deposits.

Blue Mountain and Columbia Basin Demarcation

About 4 miles northwest of Kinzua, the Blue Mountain, John Day and Columbia Basin provinces join near the old Hoover School at about 4,000 feet elevation. From that point north and east, the line of demarcation is between Blue Mountain and Columbia Basin provinces at about 3,500 feet elevation, within natural grasslands. About 22,000 acres in the Lonerock vicinity of southeastern Gilliam County lie in Blue Mountain Province. Within this segment of Blue Mountain Province is an island of John Day Province which surrounds Lonerock and covers about 7,500 acres in Gilliam County.

The line of demarcation between Blue Mountain and Columbia Basin provinces in southeastern Gilliam and southwestern Morrow counties is about 3,500 feet elevation. This elevation approximates major soil lines that are the basis for differentiating between Blue Mountain and Columbia Basin provinces.78, 85

On the Columbia Basin (north) side of this line, the major soil series are predominantly Condon, Morrow, and Lickskillet which have thin gray-brown to brown silt loam surface layers and brown silt loam or silty clay loam subsoils over basalt bedrock. On the Blue Mountain (south) side of this line, the major soil series include Waha, Wahala, and Gwin, which have thick very dark brown to black silt loam or silty clay loam surface layers and dark brown silty clay loam or clay subsoils over basalt bedrock. Obviously, these soil differences are not abrupt in the landscape but occur in a relatively narrow belt.

The significance of these major soil differences, from an ecological province perspective, is that the Blue Mountain Province soils with their darker color, thicker surface layers, and finer texture reflect, among other things, more precipitation and a colder climate than in the Columbia Basin. As a result, the composition of grasslands in Columbia Basin Province (with its more arid climate) is dominated by bluebunch wheatgrass with some Idaho fescue in the stand; whereas, on the Blue Mountain side of the line, Idaho fescue strongly dominates the composition with some bluebunch wheatgrass in the stand. There are several other significant differences between these two generalized plant communities.

Note that the line of demarcation between Blue Mountain and Columbia Basin Provinces lies along the north- and northwest-facing foothill slopes of the Blue Mountains. This northerly aspect likely is another ecological factor that helps explain soil and plant differences on the line of demarcation because of associated storm patterns, cooler temperatures, and snowpack.

The demarcation line crosses from southeastern Gilliam County to southern Morrow County about 3 miles north of Lonerock at about 3,500 feet elevation. It crosses Highway 207 about 1 mile south of Hardman and meanders northeast to just south of Lena on the South Fork Butter Creek, where the Hughes cattle ranch is headquartered. From the top of Franklin Hill, it runs east across North Fork Butter Creek and crosses Highway 395 about 8 miles south of Nye Junction. From this point, the line continues northeast along Owens Creek and lower Birch Creek and declines to about 2,000 feet elevation south of Pilot Rock. From there, the line goes northeast at about 2,000 feet elevation along the footslopes of upland foothills to Cayuse on the Umatilla River, at about 1,500 feet elevation.75, 85

Blue Mountain and Palouse Prairie Demarcation

Just on top of the hill north of Cayuse, the Blue Mountain, Columbia Basin, and Palouse provinces join. From that point, the line of demarcation between Blue Mountain and Palouse provinces runs northwest to Weston at about 2,000 feet elevation. It continues around the east side of the valley at Milton-Freewater and north into Washington at about 2,000 feet elevation. The latter part of this line is based on the soil line separating Athena silt loam and the high-rainfall phase of Walla Walla silt loam soil series, which typify the Palouse Province in Oregon, from the stony foothill soils of Blue Mountain Province.75