Distance: 5.1 miles round trip
Time: 5 to 7 hours
Elevation Change: 1,518 feet/463 meters
Season: April to November. Snow may exist on the mesa into early April. County Road 5 is usually impassible in the Mt. Trumbull area from December through February.
The Mt. Trumbull trail provides exceptional views over a vast region including the Toroweap Valley, the Grand Canyon, the Kaibab Plateau, the western Vermilion Cliffs, and the Pine Valley Mountains. Mt. Trumbull is a designated wilderness area.
The trailhead is located on Mohave County Road 5. For driving instructions see the Mt. Trumbull Scenic Loop page. The trailhead and vault toilet is next to the intersection with BLM road 1044.
The trail is well established from the trailhead up to the rim. However, once on top of the mesa the trail enters a ponderosa forest and becomes harder to follow. A 2019 lightning-caused fire burned the ground cover and bushes on the forest floor. The trail is now covered in pine needles, making it very faint in places. Look for rock cairns, notches on pine trees, or temporary orange flagging tape left behind by firefighters to indicate the trail. If you lose the trail, it is easy to walk through the open forest. Keep going uphill and you will reach the summit. Note that the actual summit is about 100 yards back from the rim. The summit is marked by a very large rock cairn, an official US Geological Survey marker, and a trail register.
Hikers need to pack in all their own water. There are no springs or streams on top of the mesa. There is also no cell phone service until the end of the trail at the north rim of Mt. Trumbull. One to two bars of Verizon 4G LTE service was reported as of September 2020. AT&T service is unknown.
Hikers may want to download the free Avenza PDF Maps app and the free WEST - 2016 Arizona Strip Visitor Map available at Avenza to your GPS-enabled smartphone. This map includes all of Parashant National Monument. Even without cell service, the GPS in the phone will show you where you are on the map using the app in case you can't find the trail.
The switchbacks from the trailhead to the rim are well maintained but good hiking boots are strongly recommended. The trail is made of rough lava rock. Coming down the steep switchbacks loose lava cinders can roll under foot and cause a fall. Leather gloves will protect your hands. Hiking poles may also be useful.
To camp on Mt. Trumbull no permit is needed and there are no established campsites. There are many areas of level ground to camp on. Because of the 2019 fire, avoid camping in areas where there are fire-killed trees. These dead trees may have had their roots burned away and can fall at any time.
Be mindful of fire restrictions during the summer. Please practice Leave No Trace on your visit to this Wilderness Area.
The Geology and Volcanism of Mt. Trumbull
Mt. Trumbull sits within the Uinkaret Volcanic Field, where over 200 eruptions have taken place over the last 3.5 million years. The field erupts infrequently. During the last million years the eruption interval has been irregular, but on average an eruption happens here about every 10,000 years. Curiously, when the Uinkaret Volcanic Field first became active 3.5 million years ago, eruptions further to the west in Parashant stopped. This includes the Shivwitz Volcanic Field that gave birth to Mt. Dellenbaugh, as well as volcanism in the Grand Wash and Black Rock Mountain.
This volcanic field is bounded by two north-south trending faults. To the east of Trumbull is the Toroweap Fault, which created the Toroweap Valley. The fault scarp itself can be seen in the photo at the top of this page. A few miles to the west is the Hurricane Fault, which created the Hurricane Cliffs and Whitmore Canyon. These are the two most active faults in Arizona. Both are capable of generating up to 7.0 magnitude earthquakes. They are considered detachment faults, formed as part of Basin and Range crustal extension. These two faults are why there is so much volcanism here. Magma uses these faults, which are weaknesses in the crust, to rise to the surface.
Most of the Colorado Plateau surface rock on the Arizona Strip is 270 million year old Kaibab limestone, formed at the bottom of an ancient Permian sea. Mt. Trumbull, however, is composed of a younger rock that sits on top of the Kaibab, called the Moenkopi. It was deposited around 240 million years ago by shallow muddy rivers that deposited sediment on a broad flat plain. Almost all of the Moenkopi on the Arizona Strip has been eroded away. What we know of as ground level is actually changing every year as erosion does its work. A curious aspect to this story is how the Moenkopi survives at Mt. Trumbull. This is because of Mt. Trumbull's ancient lava flow cap (now called basalt rock). Rain and wind are always attacking the landscape here, but the thick basalt acts as a barrier to stops erosion of the Moenkopi underneath it. On the Arizona Strip, the only places you can still see the Moenkopi are under old lava flow caps like Mt. Trumbull, Mt. Logan, Poverty Mountain, or Diamond Butte. Often at the contact between the basalt and the sedimentary rock below a zone of reddish rock is seen. This is from the heat of the lava baking the sedimentary layer it sits on. But once it cools, the basalt freezes in time what used to be ground level. The difference in elevation between these features and the Kaibab limestone can be as much as 1,500 feet, showing just how much of the Colorado Plateau has eroded away around Mt. Trumbull. As you look out from the rim, it becomes clear just how much material is now gone, either washed down the Colorado River or blown away by the wind.
The high point of Mt. Trumbull, at 8,028 feet above sea level, is the vent where lava came out of the ground 3.5 million years ago. It is also the highest point in the monument. Mt. Trumbull was perhaps the first eruption in this new volcanic field. Just imagine the 2018 eruption of Kilauea in Hawaii. That will give you some idea what eruptions are like in this volcanic field. They are mostly peaceful lava fountains that build a cinder cone, followed by a lava flow that travels a few miles and then stops. The volcanoes here are not explosive like Mt. St. Helens, which is a subduction zone volcano. Those 'Plinian' style eruptions are orders of magnitude more dangerous than what happens during an eruption here. Learn more about the volcanoes of the Colorado Plateau.
Mt. Trumbull is actually a tale of two eruptions! A second, much more recent eruption burst through the top of the Mt. Trumbull mesa. What a sight that would have been! This eruption was so high in elevation it would have been seen over a vast area, at least 100 miles in many directions, including Desert View in Grand Canyon National Park and Brian Head Peak near Cedar Breaks. This eruption has not yet been dated using radiometric tests. However, because of the lack of erosion of the cinder cone, which is in an area of high vertical relief where erosion happens quickly, the eruption likely happened in the last few hundred thousand years. The photo above of the red volcanic rock in the yellow glove is from this second eruption.
Dozens of tree-covered cinder cones can be seen surrounding Mt. Trumbull. People ask if any of the cinder cones here will erupt again. The answer is no. This is a volcanic field so each time a plume of magma rises it finds a new place to emerge. Magma follows the path of least resistance. Because this area is so tectonically active, the path of least resistance changes all the time. In the case of Mt. Trumbull, it just so happened that coming up through the mesa was the easiest path. The most recent eruption in the Uinkaret volcanic field was only about 970 years ago. Called Little Springs, it's lava flow can be seen at the top of the switchbacks. Look south on the valley floor between Mt. Logan and Mt. Trumbull for the black lava rock. While it is likely going to be thousands of years before the next eruption, there is no way to know for sure. There could be a magma plume rising right now!
Observant hikers will notice vibrant red volcanic cinders all the way from the start of the trail up to the rim. These relatively young cinders are quite different in appearance from the 3.5 million year old basalt lava cap rock of the mesa that is grey in color.
The switchbacks up the mesa cut through what would have been a very deadly place to stand during the eruption. Imagine billions of molten lava cinders falling from the sky and bouncing down the steep slope. When you reach the rim and the trail levels off, the gently rounded top of the cinder cone itself can be seen. The 2019 fire burned away many of the trees on the cone. Now imagine clouds of ash and a fountain of glowing magma 500 to 1,000-feet high coming from that cone. Deafening blasts would have filled the air as explosions of gas and magma blasted out of the earth and the thuds of molten cinders and lava bombs crashed to the ground. The stink of sulfur would have filled the air.
The very careful observer may notice that the cinders on the switchbacks are golf ball size to football size. Once on top of the mesa the cinders to the northeast of the cone are much smaller, most as tiny as peas. Curious why this is? Wind storms in this area usually come from the southwest. This means that as the lava fountain was blasting lava high into the sky, the wind didn't have an effect on the larger, heavier pieces. However, it was able to blow lighter pea-sized particles to the northeast where they piled up to great depths!
The southern section of this volcanic field has spilled lava flows repeatedly down the north wall of the Grand Canyon from Toroweap to Whitmore Canyon. 17 of these flows dammed the Colorado River in the last 850,000 years. The highest known dam was 1,400 feet high and created a lake that likely stretched upstream past Phantom Ranch. One of the most famous features of this volcanic field is Vulcans Throne, a cinder cone just south of Mt. Trumbull that sits at the edge of the Grand Canyon at Toroweap. It is only about 72,000 years old. Imagine its shower of hot cinders as they dropped down into the canyon and sizzled away as they hit the cold river water. Looking at the satellite view on Google Maps you can see the just how many dark grey lava flows have cascaded into the Grand Canyon from eruptions over time. One of them is well known to rafters, called Lava Falls.
One last thing to imagine at Mt. Trumbull is what is hidden within the mesa. As erosion continues, Trumbull's rimrock continues to fall away. This exposes more and more of the Moenkopi to the erosive forces of the elements. However, there are two secret structures hidden deep within Mt. Trumbull. These are the two volcanic necks from both of the Mt. Trumbull eruptions. Made of very erosion resistant basalt rock, they will one day be fully exposed like twin spires sticking high up above the Arizona Strip. If you have ever seen photos of another famous volcanic neck, Shiprock in New Mexico, that gives us some clue what will be revealed when the rest of Mt. Trumbull finally erodes away.
Ponderosa Woods - Once you pass the cinder cone you enter a ponderosa woodland. Some of the ponderosas here are quite large, between 24 and 48 inches in diameter. These giants may be more than 400 years old. The ponderosas were dragged to a sawmill site near the Mt. Trumbull trailhead. Most logging took place here from 1870 to 1900. By the turn of the century most of the massive trees had been cut down. The sawmill near the trailhead is long gone, but a short trail leads from the parking lot to the mill's original location. Ponderosas from Mt. Trumbull and Mt. Logan were used as timber for the St. George Temple in the 1870s as well as the Grand Gulch and other nearby mines.
As you explore Mt. Trumbull you will see that some of these magnificent giant ponderosas were left uncut. Today they are surrounded by thousands of 'dog hair' ponderosa pines, which grow tall very fast but have few branches, thin trunks, and are not very stable. A natural fire cycle would have killed most of these pines. Fire suppression through the 20th century encouraged the growth of these pines to unhealthy numbers. These thick stands of spindly pines use up water that the bigger ponderosas need. This is not what it used to look like on Mt. Trumbull. Imagine as few as seven of the giant trees per acre, with grass up to your waist. That low density of pines was also strongly influenced by Native American tribes like the Southern Paiute who lit fires in the forest. Their goal was to encourage plants to grow in burned areas to use for food or other purposes. Forest management practices over the last century dramatically changed this ecosystem. This area is now being managed to return it to a more natural condition and restore the wide-open natural feel of this forest. One way that was accomplished was to let the fire in 2019 burn over most of Mt. Trumbull. That reduced hazardous fuels on the forest floor like thick layers of pine needles and excessiver numbers of bushes. Future treatments are being studied such as possible thinning out most of the small pines.
Last updated: December 29, 2021