Saturday, May 16, 2020

Cratering - Marking the 40th Anniversary of the Mt. St. Helens Eruption

Photomural image by Richard Gordon Bowen, May 18, 1980. Courtesy of the Bowen Family.
May 18, 1980. If most people remember this date at all, they will recall it was the sunny morning that Mt. St. Helen's in southwest Washington's Cascade Mountains let loose with a powerful blast that tragically killed 57 people. The 40th anniversary of that eruption is this Monday, May 18. I found out about the blast upon ending a river trip in the Grand Canyon. But first...

... The Portland Art Museum is sponsoring an exhibit to commemorate this historic geologic event. I learned of the exhibit, now viewable virtually and online, through my friend Dixie Watkins and his wife Elaine. They sent me a link that will take you on this virtual tour, which is outstanding! This is the preamble to the exhibit and tour:

"The Portland Art Museum proudly presents this tribute to Mount St. Helens on the fortieth anniversary of the eruptions of 1980. Spanning the period from 1845 to the present, this exhibition is the first survey of works of art inspired by the mountain. Although 175 years is barely a blip in geologic time, the art bears witness to an extraordinary era in the long, cyclical life of the volcano. The beauty of Mount St. Helens has ranged from bucolic to savage. Before the eruptions, painters delighted in depicting its pleasing conical shape rising high above the verdant landscape. The 1980 eruptions challenged artists to capture the thrilling and terrifying displays of nature’s sublime power. When the smoke cleared, the new apocalyptic face of Mount St. Helens compelled the depiction of its haunting majesty. Since then, the rapid return of life to the mountain has captured the attention of photographers as well as scientists from many fields. Although the volcano seems to have reclaimed its serenity, some artists have begun to look to the future. Mount St. Helens will erupt again. We are pleased to welcome you to this celebration of a great wonder on our horizon."

*** You can view the virtual exhibit at this link: https://portlandartmuseum.org/volcano-online/.***
Paul Kane, 1810–1871) Mount St. Helens, 1849–1856. Oil on canvas. Royal Ontario Museum, Toronto
I remember the day 40 years ago. I was rowing for the very first time a raft down the Grand Canyon. It was a US Geological Survey research trip with veteran geologist Don Elston leading the way. Don was studying remnant paleo-magnetism recorded in some of Grand Canyon's rocks and he conducted river trips to access the sites. Before this trip began, he was short one boatman - and in the final moments before the trip began.

Don had open heart surgery just six months before this trip, which was to be his first since his operation. He was excited and perhaps just a bit anxious about the trip. His wife Shirley and nephew Charlie were on the trip as well.
Gary Mercado, a fellow geology student with me at Northern Arizona University, had previously rowed boats for Don in these studies. But just before the trip began, Gary received word that he got a job with the USGS in Denver. We had both just recently graduated with geology degrees the week before the trip began but now Gary needed to decline his previous commitment to row this trip. Luckily for me, he asked if I was interested in being his replacement. I jumped at the opportunity, not giving it a whole lot of forethought. In those days, I said yes to anything that sounded good, oftentimes not thinking it through (like the one and only time I jumped out of an airplane in 1976).
Gary put me in touch with Don Elston and before I knew it I was rowing a boat down the Grand Canyon!

Up to this point I had only been a passenger on the river in Grand Canyon and that was just half of a trip from Phantom Ranch on down. Like everyone else back then, you learned by doing - just get in the row seat and go. Do what I do. So after the trip started and we would scout a rapid, people would ask me what that particular rapid in Marble Canyon looked like. Not wanting to appear inexperienced, I quickly came up with the honest, but incomplete answer, that, "I've never seen this rapid at this level of water." It seemed to work. (Although to this day I'm sure many of those intelligent folks figured out that I was the new guy. I was so scared from the get go and I made too many mistakes. But I was thrilled for the opportunity to row a boat and there were so many big name geologists that were along on the trip. I remember one - Max Crittenden, one of the first geologists to ever describe metamorphic core complexes. There were others whose names I have now forgotten.

Many interesting events happened on this trip. This was the year that Glen Canyon Dam filled the Powell reservoir for the first time so there was 30,000 cfs coming down the river. It was HUGE! I was rowing a very large 22' snout boat with 12-foot oars. As skinny as I was in those days, and with no prior rowing experience, I couldn't really control the boat. One day, camp was to be made at the Clear Creek beach but I missed the pull in. Don wanted to walk up to the horizontal waterfall and look at some rocks there. It was late in the day we were to camp there. But because I missed the pull-in, we had to continue down to Phantom Ranch.

There was no way to camp there for river parties but we did take time walk up to the Ranch so Don could make a phone call. While we were there, I encountered my old Park Service boss, who was giving an orientation tour of the Ranch to the brand new Superintendent of the Park, Dick Marks. I was not on good terms with my old boss and as the formalities were exchanged between the various members of our group, I eyed my ex-boss warily, as he did me.

We left Phantom but it was too late to go vary far, so we had to find a camp fast. We stopped just a few hundred meters downstream on a cobble beach just across from the River Trail. It was illegal for river parties to camp there in those days but we really had no other choice. It was getting dark and Horn Creek Rapid loomed ahead just two miles. While we setting up camp, wouldn't you know it, the two rangers we saw at Phantom Ranch were hiking up to Indian Garden on the River Trail and stopped across the way to look at our camp. They knew who we were. When the trip was over, Don received a citation in the mail from Grand Canyon National Park for illegal camping. For years afterwards, Don always joked that the citation was labeled "Department of the Interior vs. Department of the Interior".

A few days later, I got into an eddy I could not row out of. It was just above Tapeats Creek. Round and round we went for at least 20 minutes and I became thoroughly exhausted. Finally, one of the younger geologists in my boat stepped in next to me and we each took one oar and finally made it out. Man that was big water!

Albert Bierstadt (American, born Germany, 1830–1902). Mount St. Helens, Columbia River, Oregon, 1889. 
Oil on canvas. Collection of L.D. "Brink" Brinkman, LDB Corp, Kerrville, TX

On May 18, 1980, the day that Mt. St. Helen's blew its top, we were blissfully unaware of it and getting ready for our run of Lava Falls Rapid, the biggest, meanest rapid in the whole canyon. To say I was scared to run this monster for the first time would not convey in a proper way how I felt. I was terrified. And apparently, Don had a history with this rapid that caused his wife Shirley to begin to fret as much as me. While we scouted the rapid, it was determined that Shirley would ride with me on the biggest boat, and Don's nephew,Charlie would ride in the smaller boat with him. Remember, this was just six months after Don's open heart surgery.

Finally, I got in my boat. I was hyperventilating as I pulled away from shore and entered the tongue of the rapid. I guess I was lucky to have such a large craft but one still needs to bee spot-ion for the entry through the tongue. And myriad swirling currents play havoc on smaller boats in there. I remember very little about the specific run I made. Someone on shore took a movie picture of it and I have a copy of that somewhere. But it must have been a good run because I don't remember it! At the foot of the rapid I had a hard time stopping but eventually pulled over on the left bank below Prospect Spring. We couldn't see the rapid from there but waited for the other boats in our party to come down.

As we bobbed in the eddy below the spring, time seemed to drag on forever. Where were they? Before long, Shirley started to worry that no one was coming down. "Where is Don," she repeated. I tried to comfort her as best as I could. But I started to worry as well. Shirley hadn't wanted Don to row this trip so soon after his surgery and wanted to be on the trip with him. She worried audibly that something bad had happened. I tried to calm her down.

Meanwhile, up north, Mt. St. Helens was roaring with its gigantic blast. We would not find out until the trip was over what happened, although we were all talking about it on the trip, as it had been rumbling for months. All geologists back then were excited about what might happen with the volcano.

Finally, we saw something coming down the river. It was an ice chest bobbing in the water. Uh-oh. Something else came along just after that - a life jacket! Oh no, that's not good. Shirley started to cry. I immediately pulled out into the current of the river to be of assistance anyway I could. Just by chance at that time Don came by my boat bobbing in the water. Charlie was very close to him trying to reach him in case he needed help. I pulled them both into my boat as we began to go through Son of Lava Rapid. Someone in another boat wrangled his boat ashore. He had misplaced his position in the tongue of the rapid, the swirling currents grabbed his keel and he ran right over the ledge hole! No man's land!

Forever afterwards, Shirley Elston thought of me as the one who saved her husbands' life. For the rest of our friendship, spanning many decades, I could do no wrong. She and Don took that day at Lava Falls all the way to their graves and I was honored to be invited to Don's memorial. I remain forever grateful to them both in giving me the chance to be a boatman in Grand Canyon.

Look at the online exhibit and remember Mt. St. Helens 40 years on!

Frank Gohlke (American, born 1942). Aerial view: Landslide—debris flow area—looking east toward Spirit Lake, 
5 miles north of Mount St. Helens, 1982; printed 2005. Gelatin silver print. Courtesy of Artist and Gallery Luisotti

Thursday, May 07, 2020

More Cratering in Northern Arizona - Rattlesnake Maar

Photo by Dawn Kish - From the top of the Rattlesnake scoria cone; the reddish arc behind the figure is Rattlesnake maar
An unusual and little-known landform on the eastern side of the San Francisco Volcanic Field is the Rattlesnake maar near Winona Arizona. As the Covid-19 pandemic set in, some friends, my wife and I decided to visit nearby volcanic craters — to get exercise, breathe fresh air, and hone our geologic skills. (Admittedly, I was the only geologist on these excursions and none of the others wished to hone anything of the kind. Yet they at least admitted to wanting to know more)! When I was a graduate student at Northern Arizona University in the 1980s, I took a class called Volcanology and the lab consisted of visiting a different volcano every week! It was the best lab class I ever had. Rattlesnake maar was one of the features we studied.

View of the west side of the maar where the truck is parked. We are on the rim of the maar at this location and simply walked up the gentle slope on the two-track road around to its crest. The snow-capped San Francisco stratovolcano lies in the distance to the west, with other cinder cones in between. Cinder is a term in common usage but geologists also use terms such as lapilli and scoria. All are any pea-sized ejecta that forms when droplets of molten lava are thrown into the air and cool and harden. Scoria contains more vesicles, being the basaltic equivalent of pumice. Thus, the cones can properly be referred to as cinder cones, lapilli cones, or scoria cones.

On top of the Rattlesnake maar looking west. Note the dip of the tuff to the north (right) that was thrown out when the maar erupted (see my detailed description of maar eruptions below).

Looking south to the scoria cone that formed after the tuff cone. The evidence for this is that the southern part of the tuff ring is buried beneath the scoria cone. This was a great hike. For the geologist, I include the next section on maar volcanoes.

Maar's are broad, low-relief volcanic craters found not uncommonly on Earth's surface. Check out this Wikipedia site for some examples of maar's found around the world. They form when hot magma rises into the upper crust and interacts with water. On continents this usually is groundwater but can also be lakes or rivers. When the magma encounters the water a phreatomagmatic eruption occurs. These are violent steam ejections that emplace tuff around the vent. Krakatoa in Indonesia, which erupted in 1883, is an example of an especially large and explosive phreatomagmatic eruption.


Geologists are also interested in the subsurface structure of maar's. The diagram above is used courtesy of Dr. Steve Semken at Arizona State University. It shows a typical carrot-shaped diatreme that underlies a maar volcano. One of the most famous exposed diatremes is Shiprock on the Navajo Nation in New Mexico.


Dr. Semken created this cross-section that places two different, but nearby surface features one on top of the other. They share a common ancestry but one (Shiprock) is the more deeply eroded feature. In other words, before Shiprock was so deeply eroded, it was covered by something akin to the Narbona Pass crater.

Dr. Semken, along with colleague Larry Crumpler of the New Mexico Museum of Natural History, also created this photo collage of the two features. On the bottom is an aerial photo of Shiprock with its presumed diatreme margins added. These project upwards into a second aerial photo of the Narbona Pass crater. I think this image really relates two different parts of maar formation.

This is an excerpt of the USGS geologic map - MF-1960. I have colored some of the pertinent features using the Macintosh Keynote program. The tuff ring of Rattlesnake maar is colored dark purple. Note how it is not present on the south. The Rattlesnake scoria cone is colored lighter purple and overlaps the presumed southern portion of Rattlesnake maar. The brown color denotes the lava flows that issued from the scoria cone and that flowed down the regional slope. Another scoria cone and associated lava flow (not colored), Merrill Crater, can be seen to the east of the Rattlesnake cone.

The map is called "Geologic map of the east part of the San Francisco Volcanic Field, north-central Arizona." You can access the USGS map here:  MF-1960

More cones to come! Thanks as always for reading.

Thursday, April 30, 2020

Moon Crater, San Francisco Volcanic Field, Northern Arizona

The next destination in the series, "We Are Cratering in Northern Arizona" is Moon Crater. This volcanic center is labeled as Crater 170 on Harold Colton's 1936 map in "The Basaltic Cinder Cones and Lava Flows of the San Francisco Mountain Volcanic Field" (republished in 1967), and as Vent 3031 on the USGS "Geologic Map of the East Part of the San Francisco Volcanic Field, North-Central Arizona." You can access the USGS map here:  MF-1960.


*** Note to any would-be visitor to Moon Crater: The eastern half of the cone is on private land and only the western half is open to the public as part of the Coconino National Forest. The red and green lines on the map above only denote a walking route used by the local landowners. 

 Panoramic view of the interior of Moon Crater looking east.

Annotated panoramic view of the photo above. The yellow line depicts the rim of Moon Crater. A secondary cone erupted within this larger feature and is outlined in red.

Five cinder cones are depicted in this excerpt from the USGS map MF - 1960. Moon Crater is the circular feature at bottom center. Qbb represents basaltic rocks that have normal polarity (meaning younger than 780,000 years) and are latest Pleistocene in age. The are rocks that form the cone inside the larger crater (red outline in the photo above). Qbbt represents basaltic tuff of the same age, forming the rim of Moon Crater. Qbsbp is Sunset Crater tephra that landed in the bowl of Moon Crater. It is assumed that the same deposit is already stripped from the rim of the crater.

View to the northeast from the rim of Moon Crater. Merriam Crater is the cone seen in the distant background. It may be the source for the lava flow that created Grand Falls (or the flow may have come from The Sproul, the small, dark, cloud-covered cone in front of Merriam's right shoulder.

A likely fulgurite where lightning struck a rock on top of Moon Crater and melted the heated portion.

View to the southeast of a series of beautiful cones and craters.

View to the northwest. The flat-topped mesa in the far distance is Gray Mountain.

The lone cone in the distance is Roden Crater, where artist James Turrell is shaping the entire cone into a work of art. Look at the web site here and be sure to let each page run the film (three pages).

The rocks on top of Moon Crater have been around long enough to have ventifact surfaces. These are surfaces shaped by particles that blow in the wind and abrade the rock surface.

Late afternoon light on the rim of Moon Crater.

A closer view of the north rim of the crater (foreground and skyline) and the slightly younger interior cone (right).

Descending down to the vehicles. Note the ponderosa pine trees in the valley below. This elevation marks the boundary between the ponderosa and Pinyon-Juniper eco-zones. Next on the tour is the Turkey Hills.

Sunday, April 26, 2020

We Are Cratering In Northern Arizona!

Winter photo of SP Crater, the 4th youngest cone and crater in the San Francisco Volcanic Field. It has recently been re-re-dated at about 60,000 to 70,000 years old. (Photo January 1, 2011)

You might think this blog title refers to a plea for mental health during the global pandemic. But while the heading is pandemic related, it actually involves a more in-depth exploration of various volcanic craters and cones located around my home nestled within the San Francisco Volcanic field. With all of my river trips and international excursions postponed or outright cancelled, we are positioning in place under wide-open skies of northern Arizona. And the Coconino National Forest is currently still open for exploration off trail. A group of friends and I are exploring!
Sunset Crater (Crater 41) is the youngest volcano in the San Francisco Volcanic Field and a recent redetermination of its eruptive date is constrained between 1085 and 1090 CE. You can read the paper that describes this new date here. The original date of 1064 BCE can be found in this reference.

Crater 36 - April 25, 2020
Dr. Harold S. Colton, the founder of the Museum of Northern Arizona catalogued most of the more than 600 volcanic cones and craters within the field. He gave number to many cones that had no otherl names. Crater 36 is a rather indistinct cone in a field of many cones. But it provided a beautiful hike nonetheless on a clear, April day.
The approach to the crater has views of rather mature ponderosa pines. The north flank of the San Francisco Mountain composite cone can be seen in the distance.

This is a panoramic view to the northwest from the top of Crater 36. From left to right you can see the San Francisco Mountain composite cone and dozens of rather young scoria cones. US Highway 89 is the linear gap in the trees.

The coarse cookware pot remains from the occupation of the Sinagua cultural group, which inhabited the area between 700 and 1200 CE. To understand how these people may have been affected by the Sunset Crater eruption of 1985 CE, see this paper.

A view from the west rim of Crater 36 toward the east and to O'Leary Peak, a dacite dome volcano (Crater 23 of Colton) with a K-Ar age of between 240,000-221,000 years.

Panoramic view of the interior crater.

There was early logging inside this crater and the stumps remain in this dry climate. In fact, modern-day ecologists can easily map the tree density in this forest from the time before logging began in the 1880s. This mature ponderosa was cut using a two-man cross-cut saw, as can bee seen by the bi-level cut on top of the stump. The limb debris from this felled tree lies in the background. The tree was cut likely about 120 years ago.

Medicine Valley in the middle distance. This was a wonderful hike! Next up - Moon Crater.

Monday, April 13, 2020

Announcing the Wayne and Helen Ranney Geoscience Educator Scholarship at Northern Arizona University

I have had the pleasure of traveling with many readers of this blog on geologic adventures across the globe, from Arizona to Zimbabwe, from Antarctica to Zion, or from the bottom of the Grand Canyon to the mountains of Patagonia, South America. I thank all of you for your support and interest in my work during these past 45 years! In this post I have exciting news about a scholarship that my wife and I are funding to further more geology careers in this type of work.

Sunrise on the 12 Ma laccolith at Torres del Paine National Park, Patagonia, Chile

As my work has blossomed and grown, many geologists and/or guides have asked to me how they might follow in my footsteps or perhaps even emulate my career. Unfortunately, I have to tell them that this is not as easily achieved as one would hope for. It requires being away from home a lot and it is not always easy to "break in" to the field. Thus, it is not conducive to a traditional family or career life. When I started out, there were no role models for this type of career adventure and in fact, I had no idea it was going to be a career! I just constantly said "Yes" to any jobs that came my way gradually cobbling together an international traveling gig that includes writing, guiding, and lecturing. Luckily, I did not have a family or kids to support that would encumber my choices.

Teaching geology to participants on a geology-themed 
river trip on the Colorado River in Grand Canyon, 2017

Still however, if I were granted one wish to somehow advance this type of career for others, it would be to help future Earth scientists learn about such career opportunities in sharing the joys of geologic thought with non-scientists. Modern life begs for ways to make deeper connections with this wildly beautiful and exotic planet. And while I've learned that geology is just another word for scenery, it is also another way to express sustainability, since taking the long view only helps to encourage a more proper use (and reuse) of natural resources. Not a day goes by that I do not wish that more geologists took an active role in speaking up about geology to a much wider audience. 

The Antarctic Peninsula where I have made 27 trips as a geologic lecturer

It is only appropriate then to mention a few of my fellow geologists who consistently contribute  their time and effort to advance a wider public understanding of geology. If you have not yet subscribed to the Facebook page of the Arizona Geological Survey please do so. The site is guided by  Michael Conway of the AzGS. Also, Dr. Karl Karlstrom and Dr. Laura Crossey of the University off New Mexico conceived and developed the Trail of Time at Grand Canyon National Park. Many thousands of visitors to the Park become enthralled by this linear representation of time, that sequentially tells the story of Grand Canyon's geologic history while strolling along a scenic Rim trail at the edge of the canyon. A shout-out also goes to Dr. Steve Semken at Arizona State University who has developed online virtual field trips for all to enjoy. Check out one of Dr. Semken's interactive virtual field trips here. Finally, Muhammed Qasim Mahmood administers the Learning Geology Facebook page that has outreach to literally thousands of geology enthusiasts around the world. All of these individuals and others provide continuing inspiration to me to further the outreach of geology.

Dr. Steve Semken on the Trail of Time, 
Grand Canyon National Park

A SHORT HISTORY OF MY CAREER AND DETAILS ABOUT THE SCHOLARSHIP
My two geology degrees from Northern Arizona University (B.S., 1980; M.S., 1988) launched my rather unconventional career in informal geoscience education, defined as geologic instruction at any level of learning occurring outside of a formal classroom setting. After leaving NAU in 1988, I worked as a river and trail guide in Grand Canyon (which is how I supported myself in graduate school), which ultimately led to other far-reaching work assignments around the globe. These were completed with Lindlblad Expeditions and Smithsonian Journeys. I’ve now traveled to, and lectured in almost 90 countries, all focused on the geology of those distant and quite scenic places.

Flying over the Zambezi River and Victoria Falls, the international boundary
between Zimbabwe (bottom) and Zaire (above)

As my career has gradually evolved into more writing and less traveling, my wife Helen and I desired to help current NAU geology undergrads to consider a similar career choice. We both recognize the inherent value of young geologists being exposed to as many diverse geologic features as possible, as well as the huge need in our discipline to develop knowledgeable and effective science communicators. We cherish and honor the wealth of modern geologic data, but lament that much of it is known by so few of our fellow citizens. We believe that geologic thought is empowering and transformative and want to encourage future geo-scientists to develop the tools that will allow them to effectively share their passion of geology with others.


With Helen at Grand Canyon's South Rim, 2019

This is why we created the Wayne and Helen Ranney Geoscience Educator Scholarship at NAU. We have personally committed a gift of $25,000 that will be fully funded by the year 2022. Interest from the fund will be used to support an upper level geology undergrad at NAU who will pursue some level of geoscience educator career path. Imagine the benefit to a geology student who will be able to partake in a Colorado River raft trip in Grand Canyon, or will serve as a Geologist in Residence at Grand Canyon National Park. Such are some of the possibilities that we envision for this award.

We have already funded the first two years of this five year giving commitment. And a very generous four-figure donation from one of my past alumni has allowed the principle to grow even more!  

If you would be interested in helping future geo-scientists prepare for public outreach in geology, please contribute to this fund directly at the link above.

The flow path is easy and will be obvious from there. Helen and I greatly appreciate any support you can give to this fund! Remember, your gift will live in perpetuity with only the interest used to support future Earth Scientists who engage in public outreach of geology to our society! Thank you!

The Grand Canyon of the Colorado River

Saturday, April 11, 2020

Grand Canyon Geology on Facebook Live - April 9, 2020

Some of you may have been able to tune in to a Facebook Live session I was part of on Thursday April 9, 2020. If you were not able to join us Live, here are some links to view the Q&A!


Watch on YouTube here or on Facebook here.

We had viewers and questions from as far away as Turkey, Indonesia, Pakistan, Egypt and Morocco. Folks also viewed from Prescott, Tucson, the Pacific Northwest, Georgia, New York and Grand Canyon (just to name a few).

As of April 11, this video has had 7,600+ views!

Wednesday, April 08, 2020

Facebook Live Session on Grand Canyon Geology!

Do you like the Grand Canyon? Do you have an interest in geology and Earth history? Or perhaps you are just looking for something to do during a global pandemic? If so, you may want to tune in to a Facebook Live session I will be presenting on Thursday, April 9.


The session will be conducted at 9 AM Arizona time (which is also 9 AM Pacific Daylight Time); 10 AM Mountain time; 11 AM Central time; and 12 Noon Eastern Time. (Coincidentally, it gives me great joy to list the Mountain and Pacific times first!). 

You can learn more about this event here: https://www.facebook.com/geologylearn/.


Please note: If you cannot attend the live session, it will be recorded and available for viewing at a later time!

The session will be hosted by the blog site, Learning Geology created and administered by Muhammed Qasim Mahmood, an Earth scientist living in  Lahore, Punjab Province, Pakistan. Learning Geology is a science website and a community of Earth scientists [that] share geology lessons and host Live Virtual Field Tours.

As you begin to tune into the session, you can invite others to attend and please do so! I will begin by giving a short introduction to Grand Canyon's rocks and its development. Viewers will then be able to submit written questions right on the site. This live session will last no more than 45 minutes to one hour in length. And if I am unable to answer your questions while Live, I can answer them in written form right on the site. The questions and answers will also be viewable at a later time.

The times again are:

9 AM - Arizona and Pacific Daylight Time
10 AM - Mountain Daylight Time
11 AM - Central Daylight Time
12 noon - Eastern Daylight Time
6 PM - Central European Daylight Time
9 PM - Pakistan Standard Time
2 AM - Australia Eastern Standard Time
4 AM - New Zealand Standard Time
6 AM - Hawaii Standard Time

Join us for what is certainly going to be a fascinating discussion of the geology of Earth's most magnificent gorge!

Although Grand Canyon National Park is closed during the pandemic, we will be discussing its fascinating geology on Facebook Live! Thursday, April 9 at 9 AM Arizona and Pacific time.