Road Log

0.0 (0.0)       Refer to Map 4C.1.  Intersection of Oregon Hwy 126 and Oregon Hwy 242.  Begin driving Hwy 126 west toward the hamlet of McKenzie Bridge.  As you drive, the highway descends for about half a mile from the terminal moraine deposited by the glacier occupying the White Branch of the McKenzie River during the late Pleistocene glacial maximum (Bevis et al., 2008), correlative with the Suttle Lake advance of the Cabot Creek glaciation (Scott, 1977).  The road cuts on the right-hand side of the road expose glacial till capped by moderately well-developed soil.

2.1 (2.1)       The McKenzie Bridge Ranger Station of the Willamette National Forest is on the left side of the road here.  The visitor’s center offers several natural history interpretive displays and an information desk useful for obtaining road condition and campground updates, as well as backcountry permits.

4.4 (2.3)       Refer to Map 4C.2.  To the left, lies the junction of Oregon Hwy 126 and FS Rd 2638 (Horse Creek Rd).  Remain on Hwy 126 for now, the field trip returns to the highway at this junction near the end of the route.  Shortly, you pass through McKenzie Bridge; this hamlet offers gas and groceries as well as the nearby Forest Service campgrounds of Paradise and McKenzie Bridge.

9.6 (5.2)       Refer to Map 4C.3.  Junction of Oregon Hwy 126 and FS Rd 19.  Remain on Hwy 126 for now, the field trip will return to this highway junction shortly.

Research by this author (Bevis et al., 2008) indicates that this part of the McKenzie River drainage was glaciated (Figure 4A.6).  Based on the degree of weathering of glacial deposits and comparison with Scott’s (1977) work in the nearby Metolius River watershed, this glaciation is probably correlative with the late middle Pleistocene Jack Creek glaciation and occurred at least 130,000 years ago.  At this location, the valley was occupied by ice several hundred feet thick, the glacier extending downstream for several miles to its terminus near the present village of Blue River, OR.  Lookout Ridge forms the main northern slope of the McKenzie River Valley here.  Low, rounded hills occur north and south of this junction within the valley, their shape belaying their ice-sculpted origin.  The low saddle in Lookout Ridge just downstream from here was overtopped by ice which spilled into the valley of the Blue River.

The next stop on this route will explore the glacial deposits in this saddle area.  

11.1(1.5)     Junction of Hwy 126 and FS Rd 15.  Turn right onto FS Rd 15.

12.0 (0.9)     Junction of FS Rd 15 and FS Rd 1500-105 to the left (west).  Just ahead lies a boat launch area on the Blue River Reservoir.  If the water level is low (usually in the fall through early spring) park here, and hike along the shoreline to observe outcrops of glacial till and outwash (Figure 4C.1) associated with the late middle Pleistocene glaciation of the McKenzie River Valley, likely correlative with Scott’s (1977) Jack Creek glaciation (Figure 4A.6).  Wave erosion along the shoreline has exposed well-developed soils on these glacial deposits, suggestive of their old age (relative to the glacial deposits observed at the mouth of the White Branch of the McKenzie earlier).  During this glaciation, the lobe of ice that advanced across the saddle temporarily dammed the Blue River drainage, forming a small proglacial lake upstream.  Fine-grained, stratified lacustrine sediment containing dropstones can be found along the reservior’s shoreline upstream of the boat launch.

Figure 4C.1 - Jack Creek Till at Blue Lake Res copyrighted

Figure 4C.1.  An exposure of till on the shoreline of Blue Lake Reservoir probably correlative with late middle Pleistocene glaciation.

If the water level is high, or if you desire to examine more exposures of these older glacial deposits nearby, take FS Rd 1500-105 across the saddle dam to the west.  In about half a mile, FS Rd 1500-104 can be taken upslope to the left a short distance to several good road cuts exposing glacial till; otherwise continue ahead about three-tenths of a mile to a short, shoreline access road on the right (walking north along the shoreline provides more exposures of glacial sediment).

When you have satisfied your curiosity, return to Hwy 126 and drive back to its junction with FS Rd 19 and a continuation of the field trip (mileage is counted from the first boat launch site on the Blue River Reservoir at mile 12.0).

14.4 (2.4)     Back to the junction of Hwy 126 and FS Rd 19.  Turn right (south) onto FS Rd 19.

14.8 (0.4)     Junction of FS Rd 19 and FS Rd 19-410 to the Cougar Dam hydroelectric power plant.Continue on FS Rd 19 which makes a sharp bend to the right (east) at this junction.

17.6 (2.8)     Refer to Map 4C.2.  Junction of FS Rd 19 and FS Rd 1993.  Turn left (east) onto FS Rd 1993.

Road cuts near this juncture provide excellent exposures of the Cougar Reservoir Tuffs, Tertiary volcaniclastic rocks of the Western Cascades geological province (Priest, 1983; Priest, et al., 1983).  Continuing on FS Rd 19 here will take you to the Terwilliger Hot Spring Day Use Area in just over four miles. Parking for the hot springs is on the left-hand side of the road, and the hot springs are located a short walk up the small tributary valley to the left.  If you enjoy soaking in natural hot springs, these are particularly nice, although be aware that geological features are not the only things exposed in this area.  The Terwilliger Hot Springs are located near another segment of the normal fault bounding the western edge of the Oregon High Cascades graben (Figure 4.2 and Figure 4.3; Priest, 1983; Priest, et. al., 1983).

18.0 (0.4)     Cross the dam and park in the east abutment parking area to the left.  Notice the well-developed shear zones exposed in the quarried walls above the east side of the dam (Figure 4C.2).  These are likely related to faulting that formed the Oregon High Cascades graben (Priest, 1983; Priest, et. al., 1983).  After viewing the shear zones, continue left (east-southeast) on FS Rd 1993.  Be warned, FS Rd 1993 beyond the Olallie Mountain Trailhead is prone to falling rocks and to debris on the roadway, especially early in the summer season when it has not yet been “groomed” by the Forest Service.

Figure 4C.2 - Cougar Res Shear Zones

Figure 4C.2.  Shear zones (yellow arrows) related to development of the central Oregon High Cascades graben in Cougar Reservoir Tuffs, Tertiary volcaniclastic rocks of the Western Cascades geological province as seen from the western (A) and eastern (B) abutments of Cougar Dam.

20.4 (2.4)     Refer to Map 4C.4.  Pavement ends at the Echo/East Fork Day Use Area on Cougar Reservoir.  Continue on FS Rd 1993 upslope to the left.

21.2 (0.8)     Tuffaceous (volcanic breccia) interbeds are exposed in road cuts on the left.

21.8 (0.6)     FS Rd 1993 begins traversing discontinuous outcrops of glacial deposits at approximately this location, probably related to middle late Pleistocene glaciation (Figure 4A.6), and correlative with the Jack Creek glaciation of Scott (1977).  Notice how the spacing between topographic contours broadens on the valley floor above this elevation (Map 4C.4), a probable sign of glacial scour.

24.1 (2.3)     Platy basaltic andesite is exposed in a road cut on the left here.

24.7 (0.6)     Road cuts above this location expose much “fresher” looking glacial till.  The more limited weathering and soil development of these glacial deposits suggests a younger age.  This author (Bevis et al., 2008) believes it is associated with late Pleistocene glaciation (Figure 4A.6) and correlative with the Suttle Lake (LGM) advance of the Cabot Creek glaciation (Scott, 1977).

28.4 (3.7)     Refer to Map 4C.5.  The Lowder Mountain Trailhead parking area is on the right at a sharp left-hand curve in the road.  Park here and hike to the summit of Lowder Mountain (see the Lowder Mountain Trail in Western Cascades Summit Trails under the Optional Hiking Trails following this road log for a complete description of this hike).  This stop occurs at the drainage divide between French Pete Creek to the south and the upper East Fork of the South Fork of the McKenzie River.  Note the topography (Map 4C.5); the divide area and nearby valleys exhibit clear signs of glacial sculpting.  This ridge forms a col, or saddle, between two drainages in which the ice flowed more or less in opposing directions.

This trailhead offers the first of three amazing day-hiking (or short overnight backpacking) opportunities described on this field trip.  Take your pick, or complete all three; each hike offers something slightly different, although all provide spectacular vistas of the youthful central Oregon High Cascades volcanic platform and Three Sisters stratovolcanoes to the east, and the older, more highly dissected volcanic province of the Western Cascades to the west.

Lowder Mountain, like Olallie Mountain and Horsepasture Mountain at the next two trailheads, occurs near the boundary between the youthful High Cascades and older, more dissected Western Cascades geological provinces (Figure 4.1 and Figure 4.2).  These peaks are capped by Pliocene basaltic andesite lava flows that overlie older Tertiary volcaniclastic rocks (such as those exposed near Cougar Dam), both units associated with the Western Cascades geological province.  They form the highpoints along ridges that separate the watersheds of the upper East Fork of the South Fork of the McKenzie River and Horse Creek, drainages that are also aligned with the north-trending stream valleys of the upper McKenzie River and the North Fork of the Middle Fork of the Willamette River.  In all likelihood, these features are not coincidental, but instead exhibit their similar orientations due to structural control by segments of a normal fault zone associated with the western margin of the central Oregon High Cascades graben (Figure 4.2 and Figure 4.3; Priest; 1983 and Priest et al., 1983).  Lowder Mountain’s eastern face is sheared-off by glacial action, forming a cirque at the upper end of the glaciated East Fork of the South Fork of the McKenzie River.  The cirque itself retains two small lakes surrounded by pro-talus ramparts that were probably formed during Holocene neoglaciation.

After this relatively short hike, you may either return to the junction of FS Rd 1993 and FS Rd 19, or continue on FS Rd 1993 to the east.

29.8 (1.4)     The road passes a quarry on the left that exposes platy basaltic andesite.

30.5 (0.7)     The Pat Saddle Trailhead parking area is on the right.  Park here and hike the Olallie Mountain Trail (see the Olallie Mountain Trail in Western Cascades Summit Trails under the Optional Hiking Trails section following this road log for a complete description of this hike).  The drainage divide here between French Pete Creek to the southwest and Horse Creek to the east is another col, likely the product of late Pleistocene glaciation.

Olallie Mountain forms a subdued peak at the western edge of a large, generally flat plateau that divides the deeply dissected, glaciated drainages of Horse Creek and the main stem of the McKenzie River to the north and the South Fork of the McKenzie River to the south.   The mountain’s western flank is steep and oriented north-south, aligned with the north-trending upper end of the East Fork of the South Fork of the McKenzie River; both features are probably fault controlled (Figure 4.1 and Figure 4.2).  Research by this author (Bevis et al., 2008) suggests that the plateau spreading to the east served as an ice divide for a western extension of the main Cascade Crest ice cap blanketing the Three Sisters area (Figure 4A.7) during the late Pleistocene glacial maximum (and probably earlier glaciations as well).

After taking in this wonderful hike, you may either return to the junction of FS Rd 1993 and FS Rd 19, or forge ahead on FS Rd 1993 further to the east.

31.7 (1.2)     An excellent view of the Three Sisters lies straight ahead.  These are youthful composite volcanoes built on a broad platform of older, somewhat more mafic volcanics (Figure 4.3).

In a short distance, the road wraps to the left around a spur ridge and enters the first of several small cirques eroded into the northeast flank of the main ridge separating the Horse Creek drainage (which you are now in) from the East Fork of the South Fork of the McKenzie (which you left after passing through the saddle in the ridge near the Pat Saddle Trailhead).  Numerous excellent views of the youthful central Oregon High Cascades volcanic platform and its stratovolcanoes open to the east and northeast as you traverse this dissected slope and gradually swing to the west.  The ridge is comprised of lavas and volcaniclastic deposits associated with the Western Cascades geological province, well-exposed in road cuts along the drive.

32.3 (0.6)     There is a nice exposure of youthful-looking glacial till on your left here, probably related to late Pleistocene glaciation.  Exposures of till in all of the cirques along this ridge have a similar appearance, suggesting that each of these basins was occupied by a glacial ice at this time.

32.7 (0.4)     Volcaniclastics are exposed in a road cut on the left.  These volcanic rocks and others exposed in road cuts at intervals further along the road are typical representatives of the Tertiary volcanic sequence of the Western Cascades geological province (Priest, 1983; Priest, et al., 1983).

33.6 (0.9)     This location offers basaltic andesites well-exposed in the cirque headwall to the left with a fine view of the Three Sisters Volcanoes to the right.

36.5 (2.9)     Pavement on FS Rd 1993 begins again here; the road generally improves, but watch for the large potholes.

36.8 (0.3)     A conglomerate comprised of glacial till and/or outwash likely reworked as a debris flow on this steep terrain is nicely exposed in a road cut to the left here (Figure 4C.3).

Figure 4C.3 - Debris Flow on FS Rd 1993 copyrighted Figure 4C.3.  A well-indurated, conglomeratic deposit comprised of rounded volcanic clasts which may represent a debris flow consisting of reworked glacial till and/or outwash.

37.7 (0.9)     A nice pullout on the right offers excellent views of the major composite volcanoes of the Cascades Crest from Mount Jefferson in the north to the Three Sisters in the south.

38.2 (0.5)     The slope to the left is covered in gorgeous weathered columnar-jointed boulders of basaltic andesite (Figure 4C.4).

Figure 4C.4 - Weathered Basalt Columns copyrighted

Figure 4C.4.  Weathered, basaltic andesite columns covering a hillside near Horsepasture Mountain on FS Rd 1993.

39.6 (1.4)     A road cut to the left here exposes a basaltic andesite lava flow overlying weathered volcaniclastic material (Figure 4C.5).   The lava flow is zoned into a lower, blocky portion resting upon the volcaniclastics and an upper massive portion; these zones represent a cross-section through the lava flow’s interior and base.  This zonation typically forms as the lava moves forward, its interior remaining hotter and more liquid, insolated by a cooling, congealing, more rigid flow top and bottom that is continuously broken up during flow.

Figure 4C.5 - Basaltic andesite lava flow copyrightedFigure 4C.5.  A basaltic andesite lava flow overlies weathered, volcaniclastic deposits on FS Rd 1993 at mile 39.5; the lava flow’s massive interior and blocky base are readily observed.

41.6 (2.0)     The trailhead for the Horsepasture Mountain Trail is on the left (see the Horsepasture Mountain Trail in Western Cascades Summit Trails under the Optional Hiking Trails section following this road log for a complete description of this hike).  There is only a wide spot in the road here, and the trailhead is marked by a small brown Forest Service hiking trail sign.  Park carefully along the road shoulder and take the short hike to the summit of Horsepasture Mountain.

Horsepasture Mountain shares an affinity with Lowder and Olallie Mountains in that it occurs near the boundary between the High Cascades and Western Cascades geological provinces (Figure 4.1 and Figure 4.2).  Fantastic views lie to the east and northeast of the youthful central Oregon High Cascades volcanic platform and its many stratovolcanoes.  Excellent contrasting views to the west of the older, more highly dissected volcanic province of the Western Cascades are abundant as well.  The mountain (and most of the ridge of which it is a part) is capped by Pliocene basaltic andesite lava flows that overlie older Tertiary volcaniclastic rocks, both units associated with the Western Cascades.  From the mountain’s summit, the north-south trending linear valleys of the upper McKenzie River and Horse Creek are visible, these valleys having formed along normal faults associated with the western margin of the central Oregon High Cascades graben (Priest, 1983; Priest, et al., 1983).

Horsepasture Mountain is the highest peak on this ridge segment and it affords a wonderful opportunity to observe the glaciated upper McKenzie River watershed.  Several large tributaries of the McKenzie coalesce at the northern base of Horsepasture Mountain to form the main valley of the McKenzie which stretches to the west, including the main branch of the upper McKenzie, the White Branch of the McKenzie, and Horse Creek.  During late Pleistocene glaciation, ice lobes occupied much of the tributary drainages, but did not enter the main valley of the McKenzie River (Figure 4A.7); earlier, likely during the late middle Pleistocene glaciation, ice in each tributary coalesced to form a glacier that flowed down the McKenzie as far as Blue River, Oregon (Bevis et al., 2008).

After this superb little hike, continue driving downslope (to the west) on FS Rd 1993.

42.5 (0.9)     Refer to Map 4C.1.  Great view to the northeast across the McKenzie River valley in the foreground, to the distance stratovolcanoes of Mt. Washington, Three Fingered Jack, and Mt. Jefferson.  On the opposite side of the road, volcaniclastic deposits are nicely exposed.

43.3 (0.8)     Gorgeous outcrops of interbedded, massive, basaltic andesite lavas and andesitic tuffs are nicely exposed in road cuts to the left for about the next half mile as the road rounds a 180° bend and passes through a notch in a ridge (Figure 4C.6).

Figure 4C.6 - Pyroclastic Deposits on FS Rd 1993 copyrighted

Figure 4C.6.  Tertiary volcaniclastic rocks of the Western Cascades geological province observed along FS Rd 1993 near mile 39.8.

44.4 (1.1)     Exposures of similar Tertiary lava flows and volcaniclastic deposits are found along this stretch of the road for about half a mile.

46.4 (2.0)     Refer to Map 4C.2.  The road cuts here first expose an andesitic tuff, followed shortly by a massive, basaltic andesite lava flow.

47.6 (1.2)     The road curves sharply right around a switchback here.  Note the road cut on the left that exposes a well-developed soil in weathered glacial till.  This author believes that this glacial material is associated with an older middle late Pleistocene glaciation of the McKenzie River valley (Figure 4A.6), probably correlative with the Jack Creek glaciation of Scott (1977).

50.1 (2.5)     Junction of FS Rd 1993 and FS Rd 2638 (Horse Creek Rd.).  Turn left (west) onto FS Rd 2638, almost immediately to your right is Horse Creek Campground.

51.8 (1.7)     Junction of FS Rd 2638 and Oregon Hwy 126.  Turn right (east) on Hwy126 and return to the junction of Hwy 126 and Oregon Hwy 242 to complete this field trip.

56.2 (4.4)     Refer to Map 4C.1.  Intersection of Oregon Hwy 126 and Oregon Hwy 242.  This is the end of Field Trip 4C.

Road Route Maps

Map 4C.1 - Belknap Springs web version Map 4C.1.  Color shaded-relief map of the Belknap Springs 7.5” Quadrangle containing a segment of Field Trip 4C.

Map 4C.2 - McKenzie Bridge

Map 4C.2.  Color shaded-relief map of the McKenzie Bridge 7.5” Quadrangle containing segments of Field Trip 4C.

Map 4C.3 - Blue River

Map 4C.3.  Color shaded-relief map of the Blue River 7.5” Quadrangle containing a segment of Field Trip 4C.

Map 4C.4 - Cougar Reservoir

Map 4C.4.  Color shaded-relief map of the Cougar Reservoir 7.5” Quadrangle containing segments of Field Trip 4C.

Map 4C.5 - French Mountain

Map 4C.5.  Color shaded-relief map of the French Mountain 7.5” Quadrangle containing a segment of Field Trip 4C.

Optional Hiking Trails

Western Cascades Summit Trails

Horsepasture Mountain Trail (Tr 4C.1)

This trail is the first of three relatively short day-hikes to be described in this section of the guidebook connected to Field Trip 4C whose trailheads are all within a few miles of each other on FS Rd 1993.  The sum total of these hikes provides ample opportunity to observe the transition from the geologically youthful High Cascades on the east to the older, weathered and eroded, Western Cascades on the west.  It would be difficult to tackle all three trails in a single day, but two are certainly doable; if you have but a day, this author recommends this short hike, combined with either of the longer Lowder Mountain or Olallie Mountain hikes, both in terms of distance and the diversity of scenery and geology.

The hike to Horsepasture Mountain’s summit is a quick, easy to follow, uphill climb with four switchbacks, about one and a half miles (one-way) and a tad over 900 feet of elevation gain (Map 4C.6).  As for geology, the trail itself is fairly unremarkable, but the wild flower meadows along the way (from late-June through July) keep you occupied, and the panorama of Cascades peaks from the top is superb.  When you approach the summit, a volcanic crag leering over the edge of the Horse Creek drainage, views first open up to the east and south of the Three Sisters, Mt. Bachelor, and the Cascade Crest as far south as Diamond Peak (Figure 4C.7).

Figure 4C.7 - Sharon, Isaac & Owen on Horsepasture Mtn copyrighted

Figure 4C.7.  The view that first greets you near the summit of Horsepasture Mountain; Middle Sister is in the center, with South Sister to the far right.

From the top, you can see in all directions (except where a few trees block the view); return the way you came at your leisure.  Looking to the northeast, the stratovolcanoes of Mt. Jefferson, Three Fingered Jack, and Mt. Washington are all visible in the distance, with the valley of the upper McKenzie River in the foreground (Figure 4C.8).  Belknap Crater’s broad shield pokes just above the treed ridge in front of you.  The McKenzie occupies a glacially sculpted trough formed along the western bounding fault of the Central High Cascades graben.  Contrast the relatively smooth, youthful volcanic terrain of the High Cascades east of the fault trace with the much dissected topography of the older Western Cascades to the west.  To the east, the Three Sisters and Mt. Bachelor march southward in a line along the Cascade Crest.  The volcanic platform of the High Cascades, carved by the major glaciated valleys of the White Branch of the McKenzie and Horse Creek, lie between here and the Cascade Crest.  To the southeast, Diamond Peak is just discernable in the distance, with smaller shield volcanoes of the Cascade Crest marching north toward the Three Sisters.  Nearer to your position, the dissected terrain of the High Cascades – Western Cascades transition, including the valleys of Horse Creek and the East Fork of the South Fork of the McKenzie River and peaks such as Olallie Mountain and Lowder Mountain are easily observed.  The taller promontories of Chucksney Mountain and Grasshopper Mountain, on the divide between the South Fork of the McKenzie and North Fork of the Willamette Rivers, lie beyond Olallie Mountain just to the right.

Figure 4C.8 - Mt Jeff, Three Fingered Jack & Mt Wash from Horsepasture Mtn copyrighted

Figure 4C.8.  The view to the northeast from the summit of Horsepasture Mountain; Mt. Jefferson is in the distance, with Three Fingered Jack, Mt. Washington and Belknap Crater to the right and fore.  The shadowed trough in the centeral distance is the upper McKenzie River valley.

Lowder Mountain Trail (Tr 4C.2)

This trail is the second of three relatively short day-hikes to be described in this section of the guidebook connected to Field Trip 4C whose trailheads are all within a few miles of each other on FS Rd 1993.  The sum total of these hikes provides ample opportunity to observe the transition from the geologically youthful High Cascades on the east to the older, weathered and eroded, Western Cascades on the west.  It would be difficult to tackle all three trails in a single day, but two are certainly doable; this author recommends the short hike up Horsepasture Mountain, combined with either this hike or the Olallie Mountain hike, both in terms of distance and the diversity of scenery and geology.

The hike to Lowder Mountain’s flat-topped summit is a straightforward jaunt of about three miles one-way with two short, steep sections and 900 feet of elevation gain (Map 4C.7).  After climbing an initial steep, switch-backed section, much of the next mile and a half of trail traverses gently sloping forests of Douglas fir, interspersed with wildflower meadows, a great hike in June or July.  Occasional shots across French Pete Creek’s valley offer views of Olallie Mountain and Mt. Bachelor beyond.  Expansive views of geologically-rich scenery don’t appear until trails end, however.  After the two-mile mark, make a right at a trail junction in a meadow and head up another steep section of trail to Lowder Mountain’s open summit meadow.  Once on this summit plain, the trail is obscure, marked by only a few rock cairns; however, just before the trail reenters continuous forest, cross the meadow to your right about 1000 feet to the cliffs hidden by trees on the mountain’s east side.

From your cliff-edge eerie, the peaks of the Cascade Crest from Mt. Hood to Diamond Peak are laid out in a superlative 180° panorama to the east.  However, perhaps more amazing is the nearly thousand-foot drop to Karl and Ruth Lakes at the bottom of the cirque gouged from Lowder Mountain’s eastern face (Figure 4C.9).  The small lakes are sandwiched between the cliff base and protalus ramparts, likely the product of Holocene neoglaciation that caused whole-sale expansion of glaciers and moraine building at higher elevations in the nearby High Cascades.  The upper U-shaped valley of the East Fork of the South Fork of the McKenzie River lies beyond, glaciated during the late Pleistocene.  Horsepasture Mountain (right) and O’Leary Mountain (left) occur on the ridgeline in the middle distance.  Note the generally north-trending orientation of this ridge and its intervening valleys, features probably related faults associated with growth of the central High Cascades graben between 5 and 4 million years ago.  Beyond the ridgeline lies the volcanic platform of the western High Cascades, formed of countless lava flows and pyroclastic deposits extruded in the late Pliocene and early Pleistocene.  This broad flat, carved by the major glaciated valleys of the McKenzie River drainage, slopes gradually upward to the major stratovolcanoes of the Cascade Crest.

Figure 4C.9 Lowder Mountain view copyrighted

Figure 4C.9.  View to the northeast from the top of the cirque headwall gouged into the northeast face of Lowder Mountain.

Olallie Mountain Trail (Tr 4C.3)

This trail is the last of three relatively short day-hikes to be described in this section of the guidebook connected to Field Trip 4C whose trailheads are all within a few miles of each other on FS Rd 1993.  The sum total of these hikes provides ample opportunity to observe the transition from the geologically youthful High Cascades on the east to the older, weathered and eroded, Western Cascades on the west.  It would be difficult to tackle all three trails in a single day, but hiking two is certainly feasible; this author recommends the short hike up Horsepasture Mountain, combined with either this hike or Lowder Mountain, both in terms of distance and the diversity of scenery and geology.

Olallie is the Chinook Indian jargon word for “berry”, and there are plenty of those along this trail in the latter part of August, but come in July too for the Beargrass blooms which are marvelous.  The trail ascends gradually for 1200 feet through Douglas fir forest and wildflower meadows to a bald on Olallie Mountain’s broadly rounded summit where sits an aged Forest Service fire lookout (no longer in service) (Map 4C.8).  Geologically speaking, there isn’t much to see along the way, but views from the mountain top are quite nice.  Find the trailhead at the far end of the parking area’s loop (don’t take the French Pete Creek Trail by mistake).  In a half mile, cross a small tributary of Mosquito Creek; Mosquito Lake occupies a northeast facing cirque hidden in the forest upstream to your right (Map 4C.8).  Continue another mile and a half to a trail junction.  Follow the trail to the right as it climbs through a Beargrass lily meadow, their tall white plumes blooming in July.  One and a half miles further uphill, and the trail tops out on a rare bald in the Western Cascades capped by an old fire lookout (Figure 4C.10) with a 360° panorama as your reward.  The Three Sisters stratovolcanoes lie on the Cascade Crest to the east, seemingly within reach of your hand; for Western Cascades hiking, it really doesn’t get much better than this.

Figure 4C.10 Olallie Mtn lookout copyrighted

Figure 4C.10.  The bald atop Olallie Mountain offers gorgeous views in all directions; and plan an overnight stay at the old fire lookout while you’re at it.

Olallie Mountain sits as an isolated highpoint at the western edge of the High Cascades volcanic platform on a broad, glaciated upland separating Horse Creek and the East Fork of the South Fork of the McKenzie River to the north, from the main South Fork of the McKenzie to the south (Figure 4.1).  The view of the Three Sisters stratovolcanoes across the platform to the east is unparalleled (especially at sunset – making this a nice little overnight trip) (Figure 4C.11); but on a clear day, many other major peaks of the High Cascades can be seen from Mt. Hood in the north to Diamond Peak in the south.  A great northward and westward panorama down the length of the McKenzie River valley is also available for your viewing pleasure.  Return the same way you arrived, although perhaps feeling a little better for having taken in this gorgeous site.

Figure 4C.11 View from Olallie Mtn copyrighted

Figure 4C.11.  The Three Sisters volcanoes from Olallie Mountain, so close you can almost reach out and touch them.

Optional Hiking Trail Maps

Map 4C.6 - Horsepasture Mountain Trail web version

Map 4C.6.  Color shaded-relief map of a portion of the Belknap Springs and French Mountain 7.5” Quadrangles showing the Horsepasture Mountain Trail (Tr 4C.1).

Map 4C.7 - Lowder Mountain Trail web version

Map 4C.7.  Color shaded-relief map of a portion of the Cougar Reservoir and French Mountain 7.5” Quadrangles showing the Lowder Mountain Trail (Tr 4C.2).

Map 4C.8 - Olallie Mountain Trail web version

Map 4C.8.  Color shaded-relief map of a portion of the French Mountain 7.5” Quadrangle showing the Olallie Mountain Trail (Tr 4C.3).