Yesterday's Mystery Rock Explained (Sort of...)

Yesterday's mystery rock was strange. Had I not been standing on the flanks of the largest volcano in California (and possibly in the lower 48 states), I would have guessed that the rock had been formed by boring (that's as in "digging", not "uninteresting") clams or some other creature. Many of you guessed the same, and I don't blame you at all.

The easy answer, the quickest explanation is to say that this is the surface of a boulder of vesicular basalt, the term "vesicular" referring to the presence of gas bubbles that formed during the extrusion of  lava on the Earth's surface. The boulder was being used as a vehicle barrier at the pullout for the Devil's Homestead lava flow at Lava Beds National Monument. The monument covers a portion of the northern flank of Medicine Lake Highland, a huge volcanic shield complex along the boundary between the Cascade Range and the Modoc Plateau.

The thing is, I've never seen vesicles like this before. They are uniform in size and spacing. They also looked very strange from the side: they were the top of linear tubes running through the rock. I'm not even sure the tubes and vesicles are right side up. The rock had been moved into the parking area, after all, and could have been overturned in the process.

I find references to "pipe vesicles" that form when lava flows over sources of water (the pockets of steam rise through the lava), but I'm not knowledgeable enough on the subject to say that the term applies here. If the volcanologists among you want chime in, I am all ears!

Thanks for the many responses. I love a good mystery!

A Little Rock Mystery for the Day

A little rock mystery for the day. What are we looking at, and why is it strange? The picture is about 16 inches across.

"There Can Be Other Occupants" Wait, What? Notes from the Volcano Underworld

Yeah, that's something you want to think about while stumbling around in a dark cave. And for a government sign, that is almost eloquent. I spent the weekend exploring the flanks of the largest volcano in the Cascades, and thus, I assume, in the lower 48 states (all bets are off when we speak of Hawai'i and Alaska). It's called Medicine Lake Highland, and practically no one has ever heard of it. Chances are that it could be the next volcano to erupt in the lower 48, at which time everyone will hear of it. With at least 17 eruptions in the last 12,000 years or so, it has potential.

One of the most unique aspect of Medicine Lake Highland is the prevalence of lava tubes on the mountain. Just one flank of the volcano, preserved as Lava Beds National Monument, has around 700 individual lava tubes with a combined underground distance of more than 75 miles. A cave system within the Giant Crater Flow on the south flank of the volcano can be traced for 14 miles. That's where I was exploring yesterday.

Dot Jean Cave is part of the Giant Crater tube system. Lava tubes form when the lava flow crusts over but the lava continues to flow beneath. The tube system may eventually drain, leaving behind the caves. Dot Jean is easily accessible, just off the National Forest Road 49 a few miles from the summit area. The cave is unique because it doesn't have openings at the lower end. This means that precipitation and cold air can drain into the cave, but can't drain out. Even in summer the ice that accumulates doesn't completely melt away. The ice actually kept me from exploring very far into the cave. There was an ice cascade that would be easy to slip down and very difficult to climb back up.

 It wasn't hard to get to the large ice mass at the top of the slide though, so I made my way down, while watching for the "other occupants" of the cave. What or who on Earth were they hinting at? I guess we were pretty close to Sasquatch country, so I'll figure that's who it is.

The ice mass in the upper part of the cave is large and fairly translucent. It refracts and reflects light from the cave opening above and appears to glow with an eerie blue inner light. It's almost unsettling.

It is strange to walk through a cave that has existed for less than 11,000 years. Medicine Lake Highland is a short of hybrid shield volcano that has erupted a variety of lavas, including basalt, andesite and rhyolite. The most recent eruption was only 900 years ago, and high geothermal gradients and the occasional earthquake swarm indicate that magma still lurks within the mountain. Yes, I did indeed spend some of my time on the mountain this weekend hoping to see an eruption, but no dice. This time.

Total Lunar Eclipse, Blood Moon...and the World Didn't End

I had a nice perspective on the Blood Moon Lunar Eclipse tonight from my vantage point in the parking lot of the Olive Garden in Redding, California. Mrs. Geotripper tried to be patient when I got up every 15 minutes to go outside and take another picture.

We didn't get to see the beginning of the eclipse out here on the west coast, or at least I didn't as I was driving down the mountain road from Lassen Volcanic National Park, and couldn't see the moon at all until after 8:00 PM. The boundary zone between the Sierra Nevada and Cascades is a rather prominent visual blocker to things on the eastern horizon. But we sure had a nice sunset at Manzanita Lake (see below).

The moon appears red during the highest totality because sunlight is refracted through the Earth's atmosphere and shines across the surface of the Moon. If we had no atmosphere, the Moon would go completely dark during totality. 

Columbus didn't discover that the world was round. That fact was known thousands of years ago from the shape of the Earth's shadow across the face of the Moon. One of my favorite teaching moments took place a few years ago when I asked an earth science class if they could prove that the Earth was spherical. They didn't do all that well ("we have pictures from space!"), so we all went outside and looked at an ongoing lunar eclipse!

The world didn't end (at least not yet). I always get irritated at religious claims about the end times that pop up at moments like this. I'm truly sorry that people can be so gullible about this sort of thing. If one is going to be convinced about their particular religion's claims that the world will end because of a lunar eclipse (or comet, or solar eclipse, or whatever), it's like saying that the sun is predicted to rise tomorrow and therefore the world will end. If a phenomenon is going to be convincing as a sign from God or the gods, then it should be totally unexpected. Like a solar eclipse when the moon is in some other part of the sky. Or the sun coming up in the west. Or planets changing the direction of their orbit. That would be worthy of attention.

This, by the way, is why I wasn't in some place with a view of the eastern horizon. The sunset on Lassen Peak at Manzanita Lake kind of distracted us. A little.

Summer Ramblings: The Second Largest Natural Bridge in the United States

It doesn't look so big...yet

As we drift into the last day of Summer (and it's certainly holding on around here, 100 degrees a day ago), I started looking over some of my adventures. There was our Vagabonding on Dangerous Ground in the Pacific Northwest, of course, but I also spent around four weeks exploring the Southwest, and saw incredible things and places. One of those places was Natural Bridges National Monument in Utah, and one of the things was my first hike to the second largest bridge in the United States (and probably the 7th or 10th largest in the world, depending on the strict difference between "natural bridge" and "arch"). Rainbow Bridge in Arizona is the only one that is larger. Number two is in the picture above...can you see it? It doesn't look all that big, does it?

It's called Sipapu Bridge, and it is one of three spectacular bridges in the monument. How big is it? A sense of scale is everything here. Zooming in a bit, one can notice some trees growing in the opening beneath the bridge. 

It's best to see it up close. A trail, said to be 0.6 miles long (I'm skeptical; it felt longer, especially coming back up), climbs down the cliffs to the canyon bottom near the bridge.

The pathway isn't a gentle slope. There are stairways, and ladders are used to surmount some of the short cliffs. Acrophobic people need not apply.

Midway down the canyon, some Ancestral Puebloan ruins provide a brief distraction. The small room above was probably a granary where seeds were stored. The ledge with the ruin offers a nice view of the bridge if you don't feel like going farther down (the bridge has gotten LOTS bigger, and the trail looks MUCH steeper!). I sometimes think the Pueblo people had a nice sense of location.

Those trees we saw under the bridge earlier? It's becoming apparent that we were looking at large mature Cottonwood trees. This opening is huge.

The trail winds down to the base of the bridge, and the span has become otherworldly. Although precise measurements differ a little, the official height of the opening is 220 feet (67 meters), and the width is 268 feet (82 meters). The width at the narrowest point on the bridge is 31 feet (9.5 meters). I'd never seen anything quite like it.

Natural bridges and arches are similar in ultimate appearance because openings in rock are subject to the same physical forces, but the origins of each are different. Bridges form from the direct effect of water erosion as a stream impinges against a narrow ridge where a river loops completely around (meander necks). Arches can result from the erosion and exposure of underground caverns, or from the undercutting of a narrow "fin" or wall of sandstone.

Source: Wikipedia

Sipapu Bridge to me was stunning. I've been to Natural Bridges many times in the past, but we've always taken the shorter trail to the very scenic, but much smaller, Owachomo Bridge (span 180 feet /55 meters, with a height of 106 feet/32 meters). This bridge was something else entirely. So was the hike out, a climb of 600 feet in just over a half mile. It was worth every step!

Unusual Sunrise over the Sierra Nevada Today

Sometimes there are just unusual things. I was driving into work early this morning just before the sun broke out over the Sierra Nevada. From my vantage point on the floor of the Great Valley, the rays of the sun were casting shadows on some of the smoke from the horrific wildfires that have afflicted our state in the past few weeks. The sight stopped me in my tracks. The ridge line looks out of focus, but it's not.

The mountains in the picture are probably right about the latitude of Mt. Hoffman and and the Sierra Crest above Tuolumne Meadows. It's a strange and beautiful sight brought about by tragic fires. I'd rather have the homes and forests back. More than 450 square miles have burned in the Sierra and Coast Ranges in the last few weeks.

Losing Humanity's Heritage by Fire, But Not From Burning

Mt. Konocti and Clear Lake, an archaeological treasure in Central California

I read this article by Madeleine Thomas in the Pacific Standard, and it was disturbing to say the least. It discusses the looting of archaeological sites in the Clear Lake area, in part by meth addicts. It's truly sad how low some people can go on their life's journey, and meth addiction is one of the worst ways to go. One sometimes wonders if the human wreckage can ever be salvaged, and yet it should be society's highest priority to at least try.

It's the collateral damage to our heritage as human beings that saddened me so deeply as I read more of the article. Huge disastrous wildfires have now become the status quo in California as we enter our fifth year of unprecedented drought. A natural pattern intensified by global warming, the drought has left vast swaths of California brushland and forest vulnerable to fires far more intense, and far more difficult to contain. Three major fires are burning right now, in the Coast Range north of Napa (the Valley Fire), in the Mother Lode east of Jackson (the Butte Fire), and in Kings Canyon (the Rough Fire). More than 450 square miles have burned so far. Between them, the fires have killed five people, destroyed more than 1,000 homes, and we can now look forward to flooding and mudslides if the predicted El Nino weather pattern follows expectations.

The specific problem highlighted in the article is that fire scorched lands can expose archaeological sites. This can be a good thing if the land is protected and patrolled on a regular basis. In Mesa Verde National Park, fires burned something like three-quarters of the park in a decade's time, and several thousand new archaeological sites were discovered in the aftermath. In coming years, these discoveries will provide vast amounts of new information about the Ancestral Puebloan people. It's a treasure, but a protected treasure. Anyone trying to loot sites at Mesa Verde is likely to be apprehended in short order.

California Quail at Clear Lake

Archaeology in California can be far more difficult. The earliest humans in the state didn't make stone houses, so village sites are generally harder to find and assess. In the Coast Ranges and Great Valley where many early groups lived are under private ownership, and in many cases the sites have been deeply altered, for instance by agricultural and urban development.

Clear Lake, north of the Bay Area, is an interesting and little-known part of California. It is the largest natural lake in the state (Lake Tahoe is bigger, but extends into Nevada). It developed because of faulting that formed the lake basin, along with landslides and lava flows that blocked the outlet. Nearby Mt. Konocti (4,305 feet; 1,312 m) is a composite volcano composed primarily of dacite lava that erupted around 350,000 years ago, although the latest eruptions took place only 10,000 years before the present. And people might have been there to see it.

The lake is one of the more important regions for understanding the earliest inhabitants of California. There were a number of good reasons for this. The lava flows in the area provided obsidian for toolmaking. The lake was a secure source of water (and food) even in the most intense droughts. The oak woodlands provided a secure source of food, including the acorns and the animals that consumed the acorns. People have lived in the area for upwards of 11,000-12,000 years, from the end of the last major ice age when Mammoths and Sabertooth Cats still roamed the hills.

Butterfly at Clear Lake

The fires and drought have exposed archaeological sites along the lake shore and in the surrounding hills, and looters have been committing their crimes. It is a felony to plunder an archaeological site, but there is no budget to maintain patrols, and maybe no political will to deal with the underlying problems that lead people to plunder in the first place. I'm enraged that ISIS in the Middle East is systematically destroying the heritage of humanity in Syria and Iraq, but drug addicts and criminals are doing the same thing right here in my own backyard. The despoiled artifacts in the Middle East had at least been studied and documented. Here in California we'll never know what was lost. It's a crying shame.

Can You See It? Seeking a Natural World in an Urban Setting

Can you see it? Look carefully, it's easy to miss...

We have a drainage pond on our west campus at the edge of town. It's been a mostly neglected corner of the campus, used occasionally to graze sheep from our agricultural unit. I've been exploring it for the last two years looking to photograph birds (forty species and counting). It's not far from our Science Community Center and Great Valley Museum. The museum and science teaching facility are new, and have garnered a great deal of community interest, with a planetarium, observatory, Science on a Sphere, and all kinds of science-related exhibits. The final jewel in the crown, an outdoor education laboratory, was sort of a political football in the last year or two as the bond issue that paid for these incredible educational facilities started to run short.

Luckily, there is funding in place to build the outdoor lab, with plans in place to plant native vegetation and habitat for animals that could thrive there. The California Drought, about to enter a fifth year, put the kibosh on what was to be a central attraction, a pond. No new water features, they said.

We're going to let nature decide that issue for us. We will be designing an artificial vernal pool, a habitat almost unique to our valley. Such pools only hold water after storms in the winter and spring, and give rise to a number of endemic plants and animals. In the meantime, our attention shifted to the drainage pond. It's been there since World War II and has evolved into a natural habitat, sort of a mini-wilderness on the edge of our campus. Since we can't make new ponds, we are going to make improvements to the old one, putting in walkways, and adding a platform that students and visitors can use to take water samples and observe wildlife.

It's always a thrill to see a bit of wildness in the middle of an urban environment. That's what the picture above is about. I had my own thrill of discovery as I was taking an evening walk before class. If you look at the left side of the picture, you'll see a bit of nature staring back at me.

I've seen this beautiful fox (or a parent or sibling) on just one other occasion. It's been said it was living in one of the abandoned buildings nearby, although there seems plenty of shelter in the pond area. It was comforting to know that a bit of wildness still exists nearby. The children in our region need to know that they are part of a larger environment, and it's wonderful that they just might have a chance to see a creature such as this. It might be something else, squirrels, muskrats, turtles or birds, but it will be something. I'm looking forward to the future on this campus!

Postscript: As cute as they are, the Red Foxes are not native to California. There is a threatened subspecies, the Sierra Red Fox, that lives in the higher parts of the Sierra Nevada and the Cascade Range. All others across the state were introduced more than a century ago and have proved a problem in many ecosystems, as they eat just about anything and adapt easily to new environments at the expense of native species. I don't know what role they play in our area, or if they are a problem. My feeling is that they help control rodent populations on the campus, but I'm no biologist!

Exploring the Southern Cascade Range or Yosemite National Park for College Credit! Sept. 24-28 and Oct. 9-11

Captain Jack's Stronghold, where the Modoc people held out for months against U.S. troops. The site is protected today as Lava Beds National Monument.

This message is primarily for my readers in the Modesto region, but others are invited to consider this opportunity. Modesto Junior College has an active geology field studies program that offers the chance to explore some of the best geology on the planet, in the mountains and deserts of California and other parts of the American West. The courses provide valuable field experience for geology majors and teachers of earth science, and can provide rich life experiences for people who are casually interested in geology. We have a bit of room if you wish to join us!

The opening of Skull Cave, the largest lava tube entrance in Lava Beds National Monument.

We are offering two extended overnight trips this semester. On September 24-28, we will explore the geology of California's volcanoes (Geology 185; 2 semester units), and on October 9-11, we spend three days in and around Yosemite National Park (Geology 180; 1 semester unit). Both trips involve camping out in sometimes rugged conditions, using vans supplied by the department. The cost includes the per-unit registration fee, and an additional $90 for Geology 185, and $45 for Geology 180.

Valentine Cave in Lava Beds National Monument

The trip for Geology of California's Volcanoes will include stops at Castle Crags State Park in the Klamath Mountains, Mt. Shasta (including a drive to the end of the road at 8,000 feet), Lava Beds National Monument, Medicine Lake Highland (the biggest but not highest volcano in California), and Lassen Volcanic National Park. Some challenging hikes (and cave explorations) will be offered, but not required. One will be able to complete the course without great physical exertion, although one should be in reasonably good health to be out there traveling and camping.

McArthur-Burney Falls in the Cascade Range

The Geology 180 course, Geology of the Central Sierra Nevada, will explore all of the accessible parts of Yosemite National Park, including Yosemite Valley, Tuolumne Meadows, Glacier Point, and possibly Hetch Hetchy. We will be camping at Wawona and Crane Flat during the trip.

Lassen Peak is the most recent volcano to erupt in California, in 1914-15.

If you are in the Modesto area, we are having an organizational meeting for both of the trips on Thursday, Sept. 17 at 5:30 PM in Science Community Center 326 on the West Campus of MJC. If you can't make the meeting, contact me (hayesg(at)yosemite.edu). More information can be found at http://hayesg.faculty.mjc.edu/Cascades_field_studies.html and http://hayesg.faculty.mjc.edu/Yosemite_3_day.html. Several day trips will be offered later on in the semester, to the Mother Lode (if it hasn't burned completely up), and to Pinnacles National Park and the San Andreas fault.

Vagabonding on Dangerous Ground: A Compendium of Posts

I've finished a new blog series on our exploration of the Cascadia Subduction Zone, so I've compiled all the posts in chronological order so you can get the story the correct sequence. Thanks for all the nice comments, responses, and corrections! Click on the gray titles for the post.

On the Road in the Pacific Northwest: The introduction and overview of the new blog series.

Following the Cascadia Subduction Zone on Highway 101: This post provided the geological background for understanding the hazards of living in the lands influenced by the Cascadia Subduction Zone.

In This Land of the Sasquatch There are Ancient Giants: The first leg of our journey took us through the range of the California Redwoods and the land of black bears that look suspiciously like walking ape-people.

The End is Coming (of the Cascadia Subduction Zone): The end of Cascadia is a slow process, but the zone is disappearing slowly, being replaced by the San Andreas fault. It's also a look at one of the loneliest beaches in California.

A Geologist Walks Onto a Bar in Cascadia: Exploring the unique baymouth bars along the Humboldt county coast.

Northern California's Tsunami Central: Crescent City has a tragic history of tsunamis, especially the one in 1964 that took a dozen lives and destroyed the marina and downtown areas.

This "Dismal Forest Prison" and other problems exploring the Northwest: The Pacific Northwest was particularly difficult to explore and map, at least if you weren't part of the indigenous culture. Here are some accounts of the discovery of Humboldt Bay by land.

Into the Land of Sand, and Exploding Whales: Between Coos Bay and Florence, Oregon, is the longest stretch of sand beaches and dunes in the Pacific Northwest. Yeah, and the whale thing...

Into the Realm of the Devil (and Sea Lions): There are a lot of things named for the devil on the Oregon coast for some reason. And some incredible sea caves occupied by sea lions.

Putting on a Happy Face at Dismal Nitch and Cape Disappointment: We reach the mouth of the Columbia River, where Lewis and Clark reached their goal. It's undergone a great many changes over the years.

Into the Rainforest, Seeing Something Strange...Rain: We explore the Hoh Rainforest in Olympic National Park for the first time, and encounter something strange, at least this year: rain. There was also a fire burning in the rainforest. That's not normal.

The Diverse Landscapes of Olympic National Park: Olympic is one of the most diverse of our national parks, with alpine glaciers, rainforests, and coastlines. It's spectacular.

The Salish Sea and the Strait of Juan de Fuca: Glaciers and tectonics combined to form a seaway east of Vancouver Island and the Olympic Peninsula. It's a unique ecosystem quite distinct from the Pacific Ocean just a few miles away.

Stone Rings, Glaciers, and "Dinosaurs" on the Coast of the Salish Sea: Desecrated burial mounds, avian dinosaurs, and glacial landscapes. Victoria on Vancouver is both a beautiful city and a fascinating place to explore.

Exploring North America's Southernmost Fjord: We take the ferry to the mainland, making landfall inside of the southernmost glacial fjord in North America, Howe Sound in British Columbia (defined here as on the mainland, but connected to the ocean; opinions differ!).

Landing Place of the Thunderbird and the Grimy One, the Volcanoes of British Columbia: Black Tusk and Mt. Garibaldi two of the northernmost volcanoes in the Cascade Range. I missed them last year in the rain, but saw them this time.

Controversial Stone People, Fire and Ice, and an Olympic Legacy: We made it to Whistler and the home of the 2010 Winter Olympics. The stone people were controversial, but the scenery was not. It was spectacular.

Seeing Volcanoes from the Inside Out at Siám' Smánit (Stawamus Chief): Glaciers and granite! Stawamus Chief is a dramatic granitic dome rising high above the end of Howe Sound. It was once the magma chamber of a volcano.

Our Tour of the Greatest National Park I Never Once Set Foot In: North Cascades National Park is a true primeval wilderness. No roads penetrate the park boundaries. But what incredible scenery!

The Geology that Explains Why North Cascades is a Park Divided: The Skagit River may be the most altered water course in the Pacific Northwest, but it provides 20% of Seattle's electricity. It splits a national park in two.

What's East of North (Cascades), A Brief Explore: North Cascades doesn't have all the scenery; the lands to the east are rather spectacular too, and offer some great geology.

Playing Hide and Seek with a Sleeping Monster: Mt. Baker is not the most active volcano in the Cascade Range, but it is capable of great mayhem. It even looked for awhile like it might blow back in 1975.


Danger Follows Us Home (As it does all of us): A Mt. Shasta drive-by (photo) shooting, and a wrap-up of the series. Danger is always with us no matter where we are. It's not to be feared, but respected and prepared for.