Red Mountain

In all, 23 bright eyed and bushy tailed eager hikers gathered for quick greetings, hugs among old timers and handshakes among new comers. Three additional hikers had already started their journey the day before and were camping out, since Friday, in Flagstaff. They were to meet us at the Red Mountain trailhead. They were slated to stay behind, after our day’s activities, for some additional hiking in Flagstaff the following day.

Carpools arranged, six vehicles dashed the 130 miles north to Flagstaff. We were to regroup at Target from where we would then caravan some 35 miles north to Red Mountain. As we approached our turnoff, Red Mountain was quite visible from the main road to our left.

The weather was clear in the morning with lows in the 70s. Showers were predicted for the afternoon but we encountered none. The trailhead is a quarter mile from the main road.

These two hikes scheduled for today are unique in that, contrary to traditional hikes with trails scaring the side of a mountain, or across a stretch of ponderosa forest, or a dry creek or in a canyon; these two adventure hikes take us into the inner most of an extinct volcano and a lava tube, not available anywhere else in Arizona.

Not knowing how they were formed is missing the whole essence of the discovery. It has been said that “knowledge is power” and knowing how these two sites were created makes the whole experience more interesting and memorable. Henceforth, we can all talk about these two sites with conviction without claiming to be geologists.

At this point it is appropriate to give the reading public, and our hikers, a synopsis of the geological formation of Red Mountain according to the U.S. Geological Survey and how best the geologists interpret its formation. Here is how Red Mountain appears on geology map of northern Arizona. This is Geology 101.

Red Mountain, located in the Coconino National Forest of northern Arizona, is 25 miles northwest of Flagstaff. It is a volcanic cinder cone that rises 1,000 feet above the surrounding landscape. It is unusual in having the shape of a “U”, open to the west, and in lacking the symmetrical shape of most cinder cones. In addition, a large natural amphitheater (area we hiked) cuts into the cone’s northeast flank. Erosional pillars called “hoodoos” decorate the amphitheater, and many dark mineral crystals erode out of its walls. Studies by U.S. Geological Survey (USGS) and Northern Arizona University scientists suggest that Red Mountain formed in eruptions about 740,000 years ago.

Red Mountain is one of several hundred cinder cones within a swath of volcanic landscape that extends 50 miles eastward from Williams, Arizona, through Flagstaff to the canyon of the Little Colorado River. Geologists call this belt of volcanoes the San Francisco Volcanic Field, named for San Francisco Mountain, whose tallest peak is 12,633 feet above sea level, the highest elevation in Arizona, Mount Humphreys. Red Mountain rises about 1,000 feet above the surrounding landscape, and its crest is at 7,965 feet elevation. The San Francisco Volcanic Field has been active for about 6 million years, and Red Mountain is roughly 740,000 years old.

Red Mountain is unusual in that its internal structure is exposed. This is not the case at most cinder cones in the San Francisco Volcanic Field, because erosion has not had enough time to expose their internal features. Near Red Mountain a large Forest Service sign along Highway 180 invites the motorist to exit and visit this cinder cone. A parking lot is located about a quarter mile off the highway. A gentle, uphill, 30-minute walk from the parking lot brings the visitor into a natural amphitheater carved into the northeast flank of Red Mountain. The back wall of the amphitheater is a nearly vertical 800-foot cliff, which tapers off to the right and left. Truncated layers of volcanic cinders form ledges and color bands across the amphitheater walls.

A visitor standing in the center of the amphitheater, nearly surrounded by towering cliffs of cinders, might think that this is the center of the volcano, the location of the vent where molten rock (magma) was erupted. However, the actual center of eruption was over the back wall of the amphitheater, out of sight. The amphitheater is a geologic feature that formed after the eruption ended and continues to be enlarged by erosion today.

An “ideal” cinder cone forms when eruption occurs on flat ground. nicknamed “hoodoos”. From deep within the Earth, magma charged with gas (like the “fizz” in a carbonated drink) rises through a vertical pipe-shaped conduit and erupts as a fountain of frothy lava that may spray as high as 2,000 feet into the air.

As an individual blob of this frothy molten rock flies through the air, it cools quickly enough to solidify before falling back to Earth. Many gas bubbles remain trapped in the fragments. If small, these fragments of rock are called “cinders”, and if larger, “bombs”. As eruption continues, cinders accumulate to form a conical hill. Periodically, the flanks of the growing hill may become so steep that lobes and sheets of cinders slide downward. When lava fountaining ends, a symmetrical cone-shaped hill, commonly indented by a summit crater, has been added to the landscape. Internally, the cone is a pile of loose cinders in layers that dip away from the volcano’s vent in all directions.

The origin of the Red Mountain amphitheater is something of a geologic mystery. The truncated cinder layers exposed in the amphitheater walls are clear evidence that material has been removed. However, how this removal was accomplished is not entirely clear.

It seems unlikely that the entire amphitheater was created by water erosion, because there is so little surface area to catch rainwater and snowmelt, and funnel it down channels to erode the side of the volcano. An intriguing, though speculative, possibility is that one or more steam explosions created an amphitheater=shaped hole in the side of Red Mountain shortly after eruption ceased. Newly erupted cinders probably cooled to about 600° F as they fell back to earth, but then remained well above the boiling temperature of water for some time. Rainwater seeping into the cone and circulating through the still hot cinders may have quickly deposited a strong mineral cement that bound cinders together, creating the equivalent of a sealed “pressure cooker”. Eventually, the pressure of the trapped superheated water may have exceeded the strength of that cooker, resulting in one or more steam explosions.

Two characteristics of the cinder layers seen in the amphitheater support this scenario. Although most cinder-cone volcanoes are piles of loose cinders, the cinders exposed in the walls of the amphitheater are partly cemented into hard outcrops by mineral cement. Also, the cinders range in color from nearly black to reddish and brownish tints, indicating contact and chemical interactions with hot water and steam.

Even if a steam-blast scenario is correct, the initial amphitheater opening has been enlarged by normal surface-water and wind erosion during the approximately 740,000 years since it formed. For example, here and there, especially in the western part of the amphitheater, 10- to 20-foot-tall, upward-tapering pinnacles of cinders are capped by 1 - to 3-foot-wide boulders of dense lava. The boulder “sombrero” capping each pinnacle protects the underlying cinders from erosion. Geologists call this rather bizarre type of landform an earth pinnacle or “hoodoo”. Much of the amphitheater is decorated with hoodoos and other odd-looking spires, ridges, and ribs, all of which were almost certainly sculpted by water and wind erosion.

You just passed your geology course with an A+ grade. Kudos!

At the trailhead we pause for our group picture and name introductions. There were 26 of us. No name quiz today! Only a few of us had hiked the Red Mountain before, so, for most of us this was a new adventure.

Ready, get set, start! The hike was on towards the amphitheater opening of the volcano. It was warm and the trail meandered through various vegetation present at over 7,000 feet in elevation. A camera shot to the south east and you could vividly see the San Francisco Peaks still covered with snow in mid-June.

A glance to the west and you could see the volcanic amphitheater. The last half mile, we hiked in a dry river bed. As we approached the crater, you could start seeing the red, brown and black volcanic cinder strewn all around the landscape. To the right, one can see a tall mound of loose black volcanic cinder and one courageous trailblazer, namely Jazmin, ventured to climb it. It is very loose cinder and one’s feet tend to sink in to above the ankles.

As we approached the volcano’s outer walls, it happened that a narrow part of the wall had collapsed and created a “gateway” into the entrance of the volcano, but not before climbing a manmade ladder to breach a 12 feet high wall. Once inside the volcano, we spread out in all directions to explore the inside of the crater. There were some charcoal black volcanic cones but mostly the reddish brown colors permeated the inside volcanic walls and the “cones” or “hoodoos”.

We explored the area for half an hour. Some of us had time to eat a quick snack in the shade of some very large ponderosa pine trees.

We then headed back to the trailhead but not before exiting the crater through the same ladder. Everybody wanted to have their picture taken coming down the ladder and we were happy to oblige everyone. There must have been some “magic” power to this ladder!!! And here is the ladder parade (drum roll):

We now start our 17 miles return trip to pick up FR 245 which will take us five miles west, on a dirt road full of potholes, to the Lava Tube parking lot. The latter was full of cars, a testimony to how popular the Lava Tube is with hikers and visitors of all ages.

We saddled up with our funny packs or backpacks, fastened our helmets, for those of us who brought them along, we check our flashlights and proceed to the Lava Tube entrance some 300 yards away.

At this time it would be appropriate again to take a second class in geology which we will call Geology 102. It is important to understand, to be the best of our geologists’ knowledge, how this Lava Tube was formed some 700,000 years ago in order to better appreciate the experience of hiking and exploring inside the Lava Tube.

Lumbermen working for the Saginaw and Manestee Lumber Company discovered Lava River Cave about 1915. These lumbermen made less than $2.50 per day and each day was usually 12 hours of back-breaking work. Chainsaws were not popular yet and trees were felled using axes and 2-man “buck” saws. Finding Lava River Cave was probably an exciting and welcome diversion for these hard working men of the early 1900s.

Homesteaders are said to have visited lava River Cave sometime around the turn of the century. According to historians, homesteaders would collect large quantities of ice from the cave. The ice was used for refrigeration, cooling drinks and maybe even to help create a rare summer treat, ice cream.

Lava River Cave probably formed within a few hours after a brief volcanic eruption. In comparison to other geologic events, like the cutting of a canyon or the movement of a glacier, Lava River Cave formed in the briefest of moments. Since the cave appears today much as it did shortly after its formation, it is indeed a “frozen moment” in geologic time.

Lava River Cave is a unique kind of cave known as a “lava tube”. It is the longest cave of this kind in Arizona. Geologists believe lava River Cave was formed sometime between 650,000 and 700,000 years ago when molten lava erupted from a volcano near the present day site of Michelback Ranch. When the lava came to the surface its temperature was hotter than 2,000 degrees Fahrenheit!

Lava River Cave contains a variety of outstanding lava flow features. These features also used to exist outside the cave, but have long since been washed away by wind and rain, and overgrown by plants. The lava flow features in this cave include flow ripples, splashdowns, cooling cracks and lavasicles.

Flow ripples can be observed on most of the floor throughout the last two thirds of the cave. This gives the floor the appearance of a frozen river. Actually the floor is a “frozen river” of lava which flowed through the cave shortly after the walls and ceiling hardened.

Splashdowns appear to be rocks floating on the frozen river because they actually were. Shortly after the ceiling hardened a few rocks fell into the still flowing floor and floated downstream a little ways before the floor also hardened.

Cooling cracks are long cracks in the floor, ceiling and walls. Some of these are six inches wide, three feet deep and over twenty feet long. These cracks formed as the lava cooled and hardened because lava shrinks when it cools.

Lavasicles are very small icicle-like formations which formed after the walls and ceiling hardened. For some reason a hot blast of gas shot through the tube shortly after it formed and partially re-melted the walls and ceiling. This caused drips of re-melted lava to form and quickly hardened into lavasicles.

The lava flow features within Lava River Cave may not seem particularly fragile, but they are over half a million years old and cannot be repaired or replaced.

Lava River Cave is an amazingly simple natural ice box. In fact, it could be considered the largest refrigerator in northern Arizona. On the hottest day of summer, when the temperature outside the cave is over 90 degrees, just inside the temperature is 35 degrees and sometimes there is ice!

There are two reasons that temperatures within the cave remain so cold:

First, the lava rock which formed the cave is an excellent insulator. Its dark color and very dense composition prevent heat from traveling from the surface into the cave.

Second, Lava River Cave is cold because of its general shape. The highest point of the cave is the entrance. Since hot air rises and cold air falls, cold air falls into the cave during winter and is trapped there throughout the summer.

Lava River Cave is occasionally used by animals and insects. These include crickets, beetles, porcupines, squirrels and bats. All of these creatures are shy, and since so many people visit Lava River Cave, it is rare to actually see them while in the cave. We do know that animals use the cave because their droppings can be observed beneath rocks and along the walls.

When we reached the entrance to the Lava Tube we paused for our group picture to commemorate the event. Then we proceed with our descent into the Tube through a small and rocky opening: one at a time, each of us files in line, slowly and gingerly negotiates the steep 100 feet of descent. It takes a couple of seconds for our eyes to adjust from broad daylight vision to night vision in this subterranean medium. At the cave’s opening you could feel the draft of cold air blowing out of the opening with noticeable velocity. The aforementioned history explains this phenomenon.

Finally down to the bottom of the descent, though still not a smooth bottom, one must navigate through rocky slabs, some anchored to the floor and other oscillating when you step on them.

Further inside the tube, the walk flattens out somewhat but you mostly walk on what seems to be a large field of “frozen” popcorn, the magma that got cold and froze, leaving the effect of bubbling magma frozen in history (see above).

At times you could see and feel water dripping from the cave’s ceiling. You could also see the crack or fissure in the center of the cave’s floor. You could also see large slabs of rocks that have peeled off the ceiling and sides of the tube. You can see the cracks of future slabs to pull off as water seeps in them, then freezes in the winter, ice will expand and the crack widens to the point that it is minimally attached anymore to the tube ceiling. Its sheer weight will cause it to detach from the ceiling and fall down on the tube’s floor. Hopefully, when no human is walking underneath it!

The air was cold but not terribly cold and nowhere around 40 degrees Fahrenheit at this time of the year. We did not see any critters of any kind but according to the history mentioned above, they do exist in the winter but never seen by humans because the cave is always visited by humans.

The walls of the Tube were a mixture of black, gray, white and pink colors and in one place we could even see a vandal’s graffiti. Most of the graffiti has been removed by the forest rangers.

Most of the Tube’s ceiling was 20 to 30 feet high. So, it was easy walking upright except in a couple of places. Watch out! Duck! Appropriately so, etched on the flat slab, that may have peeled off the ceiling. In this spot, the ceiling was between 4 to 5 feet high and you had to get really down to navigate. The helmets came in handy here. We all banged our heads several times against these low ceilings. Luckily, no one of those helmetless hikers hurt their head.

Most of the length of the Tube was fairly wide and there seemed to be a sense of direction for the hikers: right side - going in, and left side - going out; a reasonable subterranean highway traffic pattern. Finally, after wondering how far is the end, you reach that magical finish line, where the tube tapers off and the ceiling and the floor seem to merge, thus signaling to us that the end is here. There were many other non-trailblazers congregating at this end. We rested up for a few minutes then asked someone to take our group picture as a testimony to our achievement. Kudos to all of us!

We now proceed on our return trip out of the tube which did not seem as long as going in because psychologically, we already knew what to expect and the thought of a delicious dinner awaiting us in Flagstaff seemed to shorten the trek back.

Finally, one reaches the end or rather the beginning of the tube. You could really see the “light at the end of the tunnel” and this is not figuratively speaking. You are tired, sweaty, anxious and hungry and there’s still this daunting 100 feet of a steep climb over large boulders to the opening of the tube. You finally make it! Hooray! Thumbs up! And here is John! And here is Michael.

We rested up for a couple of minutes at the cave’s entrance and then proceed to the parking lot and on to Flagstaff for a delicious meal.

We were all very hungry and thirsty for a cold beer! We drove back to Flagstaff and patronized a Greek restaurant by the name of “Taverna”. It was a beautiful venue, modern and eye appealing. Thanks to Michael Humphrey’s recommendation. The restaurant was ready for us when we got there: tables were set up for us in an L shape in a private corner of the restaurant, dinner ware was set up and two servers were assigned to serve our group. The service was very quick and excellent and the meals were delicious with large portions with plenty to take back home for lunch the next day.

We all got home safely. It was a fun filled day, a fast moving day with 26 magnificent and fabulous Trailblazers.