A Look Back at Ten Years of Geotripping: Vagabonding on Dangerous Ground, an Exploration of Cascadia

In 2015 I wrote a blog series about driving through the "Most Dangerous Plate Boundary" in the world, but it was actually about driving through a fossil subduction zone that is exposed in the Coast Ranges, Great Valley and Sierra Nevada of Central California. In the summer of 2015, Mrs. Geotripper and I took a long journey along the entire length of a real "dangerous plate boundary", the Cascadia subduction zone, that extends from Northern California to British Columbia. The trip coincided with a media explosion over the very real possibility of a magnitude 9 earthquake along the Pacific Northwest coastline. This resulted in another blog series, Vagabonding on Dangerous Ground. Here is a compilation of the journey...

This was posted on September 13, 2015...

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 orange 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.

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.

Hunting for Fossils in the Sierra Nevada...Wait a Minute, What Fossils are there in Granite?

Photo by Mrs. Geotripper

Last night I attended a great presentation on the dinosaurs and other (more interesting) Mesozoic reptiles found in California. It was given by Dick Hilton, a former prof at my school, who is currently teaching at Sierra College in Rocklin. I was invited to head up to the Sierra Nevada to look for fossils with Dick and fellow prof Noah Hughes, and I jumped at the chance.

But...fossils? In the Sierra Nevada? Isn't the Sierra Nevada composed of granitic rock? Granite and other plutonic rocks develop from cooling magma deep in the Earth's crust, an environment that is neither conducive to life, nor to the preservation of fossils. A quick look at a geologic map reveals that the Sierra is only about three-quarters exposed granitic rock. Most of the remainder is composed of metamorphic slate and metavolcanic greenstone, with a fair amount of serpentinite (California's state rock).

Metamorphic rock is the product of taking pre-existing rock and subjecting it to extreme heat and pressure. The resulting rocks, with names like slate, phyllite, schist, marble and quartzite, often bear little resemblance to their previous form, their protoliths. Any fossils that might have been part of the original rock are often destroyed in the process. There is a rich record of tectonic events leading to the formation of the Western Metamorphic Belt, a story too complex to even summarize in a short blog post. Long story short, fossils shouldn't be found in the Sierra Nevada. The rocks have been too distorted and altered. For the most part...

The Mariposa formation is a deposit that formed on the bottom of a deep sea off the coast of California in Jurassic time. The shoreline lay east of where it is today, and the Sierra Nevada was a different place: a series of active volcanoes led to a coastal forest. Dinosaurs, pterosaurs, and primitive mammals roamed the forests and floodplains. In the sea, large swimming reptiles including plesiosaurs and ichthyosaurs were to be found. The Mariposa is somewhat less altered than many other rocks of the metamorphic belt, and because of this, a few fossils have been found, fossils that enabled geologist to figure out the age of the rocks, an important step in unraveling the complex geologic history of the region.

The Mariposa formation is exposed along Highway 49, and we were searching for fossils in the vicinity of Don Pedro Reservoir. To my great delight, after a bit of sweating and slipping down wet grassy slopes we found some interesting specimens.

The most common fossils include the bivalve Buchia, an important diagnostic fossil indicating a Jurassic age for the unit.

I almost missed a small belemnite, which looks a bit like a fossilized cigar. The cylindrical fossil is the internal shell of a squid-like creature.

The prize find for me on this day was a small ammonite. Ammonites are relatives to the pearly nautilus which lives in today's seas. They can be thought of as an octopi with a shell. I have a spotty history with ammonites in the sense that for the last quarter century, I haven't been able to find any, and it hasn't been for lack of trying. I once stood in front of a productive outcrop with a noted paleontologist, and I watched him walk up and pull an ammonite out of the cliff face. I've been back to that spot many times over the last twenty years, and I have yet to find another. But today, I flipped a rock over, and there it was, a little tiny ammonite.

I didn't make that best find of the day, though. That honor belonged to Noah, my fellow prof at Modesto Junior College. The sample below shows a sprig of a species of redwood tree. This is an astounding find to me. Redwoods survive today in just three places in the world, on the northern California coast, in the Sierra Nevada, and in a small grove in China. But the trees once ranged across the northern hemisphere, and as Noah's find shows, they have been around for more than 160 million years. Think of it this way: dinosaurs once roamed through forests of redwood trees. And here in the rock was a distant ancestor to the Sequoia trees that grow just a few miles up the hill from our fossil site.

We were reminded of dinosaurs one more time today as we were driving home. We passed a large herd of modern dinosaurs who were displaying the kind of herd behavior that we think the large plant-eating dinosaurs displayed during the Mesozoic Era. Luckily they didn't attack!

Dick Hilton wrote the guide about the history of Mesozoic reptiles in the California region, and the book remains the best source of info about mosasaurs, ichthyosaurs, plesiosaurs, and the handful of dinosaur species found in the state. You can get the book at http://www.ucpress.edu/book.php?isbn=9780520233157 or any other online seller. I give it my highest recommendation!