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“Bite-Size Bits of Local, National, and Global History”
“Bite-Size Bits of Local, National, and Global History”
Near La Pine in Deschutes County, Oregon — The American West (Northwest)
 

Glass Menagerie

 
 
Glass Menagerie Marker image. Click for full size.
By Duane Hall, August 29, 2008
1. Glass Menagerie Marker
Inscription. The entire surface of this remarkable flow is glass, a liquid that cooled without crystallizing. The striking differences you see from rock to rock are due to the number and size of bubbles.

Why is everything glass?
Whether natural or synthetic, the primary ingredient in glass is silica (silicon dioxide). The obsidian and pumice of this lava flow contain about 73% silica, like most window glass does. In a hot, molten state, silicaís atoms tend to stick together and create webs of molecules that slow down the movement of all atoms. The surface of this lava flow cooled off before its atoms had time to organize into crystals, so we are left with glass instead.

Flow Facts
Age†††1300 years, Central Oregonís most recent eruption
Length†††1.0 miles (1.6 km)
Area†††1.1 square miles (2.9 sq km)††640 football fields or 400 soccer fields
Thickness†††Average of 150 feet (45 m). Height of a 17-story building
Flow Surface†††About 10% obsidian and 90% pumice (frothy obsidian)
Rocky Type†††A glassy variety of rhyolite (rhyolite is a volcanic rock with at least 72% silica)

Why is obsidian black? Like a drop of black ink in a glass of clear water, tiny magnetite crystals (iron oxide) give obsidian a black tint.

(Graphic
Big Obsidian Flow image. Click for full size.
By Duane Hall, August 29, 2008
2. Big Obsidian Flow
Paulina Lake in background
Captions)

Crystal†††Organized atom in crystals
versus
Glass†††Disorganized atoms in glass and obsidian

Obsidian†††Solid glass with no bubbles
Pumice†††Frothy glass with small bubbles (nearly white pumice)
Pumice†††Frothy glass with big bubbles (medium to dark gray pumice)
 
Erected by United States Forest Service.
 
Location. 43° 42.313′ N, 121° 14.125′ W. Marker is near La Pine, Oregon, in Deschutes County. Marker can be reached from Paulina Lake Road (NF-21) 0.7 miles east of National Forest Service Road 567 (NF-567). Click for map. Marker is located on the Big Obisidian Flow Trail in the Newberry Crater unit of Newberry National Volcanic Monument; the above directions are to the intersection of Paulina Lake Road and the driveway to the Big Obsidian Flow parking lot. Marker is in this post office area: La Pine OR 97739, United States of America.
 
Other nearby markers. At least 5 other markers are within 15 miles of this marker, measured as the crow flies. The Eruption (within shouting distance of this marker); Big Obsidian Flow (about 400 feet away, measured in a direct line); A Special Place on the Planet (about 800 feet away);
Layer of Obsidian Sandwiched Between Pumice image. Click for full size.
By Duane Hall, August 29, 2008
3. Layer of Obsidian Sandwiched Between Pumice
Lava River Cave (approx. 14.7 miles away); Some Lava Flows Build Their Own Pipelines (approx. 14.7 miles away).
 
More about this marker. Marker is the second of seven interpretive signs along the Big Obsidian Flow Trail.
 
Categories. Natural Features
 
Big Obsidian Flow image. Click for full size.
By Duane Hall, August 29, 2008
4. Big Obsidian Flow
Paulina Peak in background
 
 
Credits. This page originally submitted on , by Duane Hall of Abilene, Texas. This page has been viewed 281 times since then and 3 times this year. Photos:   1, 2, 3, 4. submitted on , by Duane Hall of Abilene, Texas. This page was last revised on June 16, 2016.
 
Editor’s want-list for this marker. Photo of wide-view of marker and surroundings. Photos of markers along trail missing from HMDB. • Can you help?
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