HW-180
Petrified Forest National Park to Holbrook Arizona


0.0  Entering Petrified Forest National Park.

0.2  Road Into the Visitors Center. The park is a fee area. Removal of petrified wood or anything from the park is strictly prohibited. Taponi Point is to the north in the Petrified Forest Member of the Chinle and is flanked by spectacular badland topography beneath a protecting layer of basalt debris (fig. 4A.1).

1.5  Climb onto the basaltic layer of Taponi Point.

Figure 4A.1. View northwestward to Taponi Point from Mile 0.5. Taponi Point is protected by a layer of resistant basaltic debris. The badlands below the point are carved in the Petrified Forest Member of the Chinle Formation.


1.7  View point at Taponi Point provides a badland panorama toward the north.

1.9  Tawa Point Lookout, Kachina Point, and Administrative Offices. Bicentennial Travel Center.

2.4  Rejoin the main park road.

2.5  Side road to Chindo Point (0.2 miles).

3.1  Side road to Pintado Point (0.1 miles). Pintado Point provides a panoramic view of the irregular topography of the Painted Desert to the north. Continue south into the Petrified Forest area, away from the Painted Desert section of the park.

3.4  Double road cuts through basaltic lavas at the upper edge of the escarpment. The lavas have protected this northern promontory of the park.

4.3  Nizhoni Point View Area. The thick volcanic cover shows very well to the north from here.

4.6  Whipple Point parking area.

5.0  Lacey Point (fig. 4A.2). The thick area of volcanic debris to the north is apparently related to the Hopi Butte volcanic center which is off to the west. Debris spread eastward over Chinle beds. The highway to the south swings away from the escarpment and is still on the upper beds of the Chinle Formation.

Figure 4A.2. View north from Lacy Point at Mile 5.0. Varicolored mudstone and sandstone of the Chinle Formation form the badlands in the foreground. The resistant dark layer along the plateau crest is of basaltic debris derived from the Hopi Buttes volcanic center to the northwest. Badland topography, such as this, is characteristic of the Painted Desert section of the national park.


6.2  Center of the Bridge Over Interstate Highway 40. There is no access to the interstate from here. The park road descends through short grass prairies, still in Chinle beds, down toward the broad divide and valley of the Little Colorado River. To the east the upper red member of the Chinle beds shows very well above the light-colored badland forming unit that contains the fossil wood in the park. These rocks are dipping northward into Black Mesa Basin so as we go toward the south we will see older and older parts of the formation.

10.7  Bridge Over the Atchison, Topeka and Santa Fe Railroad Tracks. The road descends now into the floodplain and valley of the very sandy Little Colorado River. Sonsela Sandstone is visible in the bluffs immediately beyond the bridge to the west.

11.2  Center of the bridge over the Little Colorado River. Indian ruins on the promontory on top of the Sonsela Sandstone, east of the road, are mortarless rock-on-rock type constructions.

12.3  Junction West to Newspaper Rock, a series of petroglyphs scratched into the desert varnish-covered sandstones of the Chinle beds. (0.3 miles).

13.5  Purple and ashy gray tuffaceous or bentonitic shales in the lower part of the Petrified Forest Member of the Chinle Formation, here armoured with brownish iron-stained concretions.

14.4  The Teepees are erosional remnants in the Chinle Formation (fig. 4A.3). Chinle Formation here appears to be principally lacustrine, with a few fluvial deltaic light-colored sandstone beds forming resistant units within the clay shales. A short distance beyond is the side road east to Blue Mesa, a volcanic remnant on top of the light-colored Chinle beds.

Figure 4A.3. The Teepees at approximately Mile 14. These triangular hills are remnants of Petrified Forest Member of the Chinle Formation and show the characteristic very complex drainage that is usually developed on the bentonitic mudstones and shales of the unit.


17.0  Cross one of the sandy washes. These washes become torrents during summer thundershowers where the ground absorbs so little water.

18.0  The park road climbs up through the Sonsela Sandstone, a light-colored sand stone here rimming the mesa, which divides the Petrified Forest Member into an upper and a lower unit.

18.4  Side road east to Agate Bridge (0.1 mile). Agate Bridge is formed of a fossil log (fig. 4A.4) abandoned in the Sonsela Sandstone. The log now spans a gully carved beneath it, so that the petrified log forms a bridge over the narrow gorge.

Figure 4A.4.Agate Bridge is a single fossil log, here bridging across a narrow gorge cut in the light-colored Sonsela Sandstone.


19.1  Jasper Forest View Point (0.2 miles). Blocks of Sonsela Sandstone are weathering out and some have logs in place. Other logs are the colored rubble over the exposed clay surface beneath the view point (fig. 4A.5). Continue south toward the Petrified Forest section headquarters of the park.

19.7  Cross a sandy shallow arroyo.

20.8  Crystal Forest Parking Area. The hike around some of the well-exposed fossil trunks is well worth the time. The highway to the south is lined by large fragments of fossil wood. Entire trunks are portrayed in sections.

21.8  Particularly large log along side the parking area on the west.

Figure 4A.5.View north from Jasper Forest Viewpoint. Sonsela Sandstone forms the resistant cap and the rocks immediately in the foreground. Dark angular blocks are large fragments of silicified fossil wood which have weathered out of the sandstone and the underlying shales.


22.4  Climb up to the Sonsela Sandstone terrace again. The Flat Tops are a mesa capped by a resistant sandstone in the upper part of the Chinle Formation.

26.6  Side Road to the East to Long Logs and Agate House. Turn toward the west across sandy arroya and into the Visitors Center, Museum and Service Area for the south section of the park.

26.8  Visitors Center. It is well worth the time to walk around the trail, west of the visitors center, to view some of the large logs (fig. 4A.6) and large fragments of spectacularly colored fossil wood (fig. 4A.7). Turn south toward the exit in front of the museum. The road descends through the abundant fossil wood out of the visitors center area.

28.5  Check out station at the south end of the park area.

29.0  Leaving Petrified Forest National Park.

Figure 4A.6. Large logs in Chinle beds along the trail west of the museum and visitors center at the south entrance to the park. The woody texture and exterior of the logs is immediately apparent.


Figure 4A.7.Cross sections of large logs, looking toward the northeast to the museum service area at the visitors center, near the south entrance into the park. General size is indicated by the couple, toward the left, behind the logs.


29.2  Junction of the park road and U.S. Highway 180. Turn west toward Holbrook and Flagstaff on U.S. Highway 180. A shop specializing in fossil wood is located west of the junction on the south side of the highway. The highway continues westward across short grass prairies, here on the lower part of the Chinle Formation.

34.6  U.S. Highway 180 bends between two drainages. Double road cuts are in the lower part of the Chinle Formation but the formation is poorly exposed in broad short grass prairies. The small pinnacle far to the south is an outlier of Chinle beds on the older rocks.

37.8  Summit Area. The highway is still in Chinle Formation. To the northwest can be seen the Hopi Buttes as the irregular patches on the skyline. The buttes mark a volcanic center, a series of lava flows, volcanic cones as well as piercement and collapsed type diatremes.

44.0  Cross the Little Colorado River with white sandstones exposed at the bridge abutments, with Moenkopi beds extensively exposed above. The highway continues westward through Moenkopi beds and small hills to the north are also in Moenkopi Formation, overlain by resistant Holbrook Sandstone.

46.8  Entering Holbrook, elevation 5,080 feet. Junction of U.S. Highway 180 with Arizona state Highway 77. Turn north toward downtown Holbrook.

47.7  Cross the Little Colorado River at the south edge of the business district. Note the levees to protect the town from flooding of the Little Colorado River.

47.9  Turn north into downtown Holbrook.

48.0  Cross Atchison, Topeka and Santa Fe Railroad tracks.

48.1  Highway Junction in Downtown Holbrook. End of HW-180 Road Guide..





from J. Keith Rigby, by Field Guide: Northern/Southern Colorado Plateau, Kendall/Hunt Pub. Co., 1976, 207 pages -Purchase Information
used by author's permission