Great Plain

Origin at the maintained structure that terminates the Divide Transit route. The track descends eastward from the foothills through piñon-juniper woodland, then into open grassland. Elevation drops from 1,600 m to approximately 1,100 m over this segment. Road surface is initially gravel on the former forest road, transitioning to compacted soil with grass encroachment as the terrain flattens. A series of dry washes cross the route, oriented north-south. Most are shallow (100–200 mm) with firm sandy bottoms. The wash at km 210 is deeper—400 mm, soft substrate, differential lock recommended. Beyond km 240, the terrain opens completely. Grass height reaches 1 m in places during late summer. The former road is still traceable as a slight depression in the grass, but the track is not distinct. Navigation by compass bearing and distant landmarks.

Surface

15% degraded asphalt, 30% gravel, 55% soil/grass

Max. gradient

12% (initial descent)

Obstacles

2 >300 mm (wash crossings)

Trackless grassland. No maintained or discernible road surface for this entire segment. Navigation is by compass, landmark, and odometer. Dominant landmarks are isolated buttes visible from considerable distance: a flat-topped mesa at bearing 088° from km 280 (visible for approximately 60 km), a pair of sandstone pillars at km 440 (approximately 30 m height, visible from 20 km), and a low escarpment running north-south at km 560. The terrain is almost flat—gradient rarely exceeds 3%. Surface is mixed grass and soil, with occasional patches of exposed clay. Bearing capacity is generally adequate on dry ground. After sustained rain, the clay patches become impassable. Tire pressure should be reduced to 150 kPa for traction on grass surfaces. Ground-nesting birds and burrowing animals create holes up to 200 mm diameter at irregular intervals. Speed should be limited to 30 km/h to allow detection and avoidance.

Surface

85% grass/soil, 10% exposed clay, 5% sand

Max. gradient

3%

Obstacles

2 >300 mm (erosion gullies at watercourse crossings)

Dry riverbed country. The route crosses a series of seasonal watercourses, most running roughly north-south. The terrain undulates gently between the watercourses. Eroded sandstone formations appear at km 620—low mesas and pillars, 10–40 m in height, useful as navigation landmarks. The dry riverbed crossing at km 740 is the critical obstacle on this route. Width: approximately 200 m. Substrate is alluvial silt and clay. When dry, the surface has a hard crust that supports vehicle weight. When saturated (after upstream rainfall), bearing capacity drops below 3,000 kg. A vehicle will sink to the axle. The condition is not always apparent from the surface—the crust may appear intact while the substrate beneath is saturated. Test bearing capacity before crossing. If substrate is saturated, the northern detour adds 60 km and crosses the riverbed at a narrower point with a gravel bottom.

Surface

5% degraded asphalt, 20% gravel, 60% soil/grass, 15% sand/silt

Max. gradient

6%

Max. ford

550 mm (spring, at active crossings)

Obstacles

3 >300 mm / 2 >500 mm (riverbed crossing, wash banks)

Transition zone. The grassland becomes taller and denser as annual rainfall increases to the east. Scattered hardwood trees appear—oak, elm, cottonwood along watercourses. A faint track reappears at approximately km 900: vehicle-width compression in the grass, consistent heading, previously traversed. The track becomes more distinct as it approaches the former road network. By km 1,100, a degraded two-lane road is discernible—asphalt fragments, road shoulders, occasional post remnants. Stream crossings are more frequent and carry more water than the western watercourses. The crossing at km 1,050 is 350 mm at seasonal median. All crossings in this segment have gravel or cobble bottoms; traction is adequate. At km 1,180, the remains of a former settlement: concrete foundations in a grid pattern, a water tower (steel, standing, tank intact), road surfaces visible beneath grass. No standing structures above foundation level.

Surface

15% degraded asphalt, 35% gravel, 50% soil/grass

Max. gradient

5%

Max. ford

350 mm (+200 mm spring)

Obstacles

1 >300 mm (collapsed culvert at stream crossing)

Eastern grassland and scattered hardwood. The former road surface is increasingly intact. Asphalt stretches of 10–20 km with grass growing through the joints but the surface still supportable. Speed can increase on these stretches; surface condition is adequate for 60 km/h. Tree density increases to the east. Cottonwood and oak in bottomland, grass on the rises. Three significant stream crossings in this segment: km 1,280 (250 mm, gravel bottom), km 1,380 (300 mm, mud bottom, momentum required), and km 1,480 (400 mm, cobble bottom, bridge abutments visible but no deck). The terrain is gently rolling—5–8% grades on the rises and descents. Navigation is straightforward; the road is traceable and landmarks (tree lines, rises, watercourses) are plentiful.

Surface

25% degraded asphalt, 30% gravel, 45% soil/grass

Max. gradient

8%

Max. ford

400 mm (+250 mm spring)

Obstacles

0 >300 mm

Approach to the terminus river. Terrain flattens to a broad floodplain. Tree density increases—mature hardwood forest in the bottomland, with understory clearing suggesting periodic flooding. The road follows a former highway alignment for the final 100 km. Road surface is degraded but continuous asphalt, passable at 40–60 km/h with attention to potholes and vegetation. At km 1,760 the river is visible from a low bluff: a broad north-south watercourse, approximately 800 m wide at this point. The bridge is at km 1,800: a steel truss bridge, approximately 900 m total span with concrete piers. Deck is intact—steel grating over the main spans, concrete approach ramps. Load capacity verified at 10,000 kg. Some deck grating is corroded but structurally sound. The bridge is the terminus of this route. Beyond the bridge, the eastern forest continues.

Surface

55% degraded asphalt, 25% gravel, 20% soil

Max. gradient

4%

Obstacles

0 >300 mm