The Anatomy of a Volcano

Posted on 20 September 2021

Over the past few months, the Skida team's fascination with volcanoes has grown in anticipation of our new collection launch, Blooming & Awakening. The Cascade Volcanoes served as the initial inspiration and, later, shoot location of this fresh collection of prints. To Pacific Northwest locals, these gigantic mountains are normal parts of the landscape. For us East Coast natives, exploring a volcano for recreation seemed a foreign concept.

To get a better understanding of the ins and outs of these geological phenoms, we turned to one of our in-house designers and long-time Oregon resident, Paget Rathbun, who felt a special connection with this collection since joining the team last spring. Take it away, Paget! 

Anatomy of a Volcano

When I was nine years old, my family packed up our house in Chittenden, Vermont, and headed West to put down roots in Bend, Oregon. My father works in the ski business, so my family constantly moved from one ski town to another (not the worst thing to happen!). When we got to Oregon, I expected the landscape to be similar to Vermont or Colorado, where I was born. I couldn't have been more shocked to see all the black rocks and tall, pointy mountains surrounding Bend. When I found out that these mountains were actually volcanoes, I was scared and excited at the same time. It seemed strange to me that this was the typical geology in the Pacific Northwest, especially coming from Vermont where the tallest mountain is only 4,393 feet.

After spending 10 years in Oregon, I became desensitized to the fact that I lived in an area with active volcanoes and spent time immersing myself in the varied landscapes they offer. I skied down these volcanoes and hiked up them (once during a butterfly migration!). I soaked in the natural hot springs surrounding the volcanoes, and spelunked in their lava tubes. 

The Pacific Northwest is a special place, and the Cascade Volcanoes have an incredible history. So what are they all about, and how did they form?

Photography by Paget Rathbun.
I shot these photos during a hike up South Sister in the summer of 2017. We were pleasantly surprised to find ourselves hiking through a monarch butterfly migration! All photos shot on Lomochrome Purple 35mm film. 


The Cascade Volcanoes
A straight line of snow-covered volcanoes, known as the Cascade Volcanoes, stretches across the Pacific Northwest landscape. These volcanoes are hundreds of thousands of years old, and almost every mountain in Oregon is volcanic.  

 

Anatomy of a Volcano

So, why do the Cascade Volcanoes exist where they do? The short answer is the Cascadia Subduction Zone. The Juan de Fuca plate is within this zone, which is a spreading center where brand new earth is being created.

The Cascade Volcanoes do not exist because the Juan de Fuca plate is melting. Rather, the Juan de Fuca plate has existed as an oceanic plate for millions of years and has wet sediment on top of it. This sediment goes down with the plate (about a hundred kilometers below the earth's surface) and starts to boil, then is added to the mantle, which melts it so it becomes magma. It rises and explodes. Thus, the Cascade Volcanoes!

Types of Volcanoes

 

Composite Volcanoes

Mt. Hood, Broken Top, the Three Sisters, Mt. Adams and Mount Rainier are all composite volcanoes which means they are tall and pointy. You can usually see volcanic layers on these mountains due to lava flowing down the mountain in the past. In the summer, you might notice these volcanoes have hydrothermal alterations in the form of orange, yellow and purple rocks. This happens because hot fluids are constantly moving through the rocks, altering them and creating these vivid colors. Hydrothermal alteration is also a sign that the volcano is rotting and its surface is becoming weak.

Shield Volcanoes




Belknap Crater, Mt. Jefferson, Mt. Washington, Tumalo Mountain, Mt. Bachelor and Black Crater are examples of shield volcanoes. The volcanoes are mainly made of lava flows and are domed with gently sloping sides.

 

Cinder Cone Volcanoes


Next up, cinder cone volcanoes. Cinder cones also have lava flows and are made up of igneous rock and cinder. There is usually a small crater at the top of these volcanoes.


Calderas



Crater Lake can be argued to be a volcano too, but it is a caldera; Newberry Crater also has calderas. Unlike a crater, a caldera is when the volcano erupted and collapsed into itself. Fun fact! Volcanoes can grow inside other volcanoes, like Wizard Island, a cinder cone inside Crater Lake. The vivid blue hues of Crater Lake inspired our new print, Caldera.

Photography by Paget Rathbun.
Left: Hiking up South Sister in July 2017. Right: A hazy hike up Broken Top.



How do you know you are on a volcano?
Geologists rely on looking at rocks! Tuff is one indication that you are on a volcano. Very deadly pyroclastic flows create this rock. It is made of chunks of other rocks, specifically pumice (very soft rock). Smith Rock is an extraordinary example of Tuff. It is harder than most Tuff, and that's why it is climbable.

Basalt is another indication that you are on a volcano. This is your classic "lava rock." It is black and has bubbles in it from gas escaping it. You would also see a lot of Cinder on a volcano. Cinder is chemically identical to basalt and is made of basalt, but it is frothy, meaning there are even more gas bubbles. It went through the fire fountaining process, which is why it has its color and so many holes in it.

Photography by Paget Rathbun.
I took these photos on an incredibly smokey hike up Broken Top mountain in August 2018.

My time spent in Oregon shaped who I am today. It opened me up to an outdoor recreation lifestyle and allowed me to explore so much of its volcanic landscape. I made friends in these mountains, challenged and learned about myself in them, and connected to nature.

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