Lava Finds a New Path - Deschutes County, Oregon
Posted by: 
Volcanoguy
N 43° 54.863 W 121° 21.464
10T E 631857 N 4863674
This geology sign is located along The Trail of the Molten Land at Lava Lands Visitor Center.
Waymark Code: WMD5GN
Location: Oregon, United States
Date Posted: 11/21/2011
Views: 13
Geology sign about the breach on Lava Butte along the Trail of the Molten Land. Sign was installed in October 2011 as part of an ADA upgrade of the trail.
Marker Name: Lava Finds a New Path
Marker Text: The Breach
If you were standing here at this point 7,000 years ago . . . LOOK OUT! Even though the more violent activity at the top of the cinder cone had slowed down, a bit of rumbling was still taking place inside. After a large amount of has had depleted from the vent and no longer shot molten debris out of the top, rising magma found the weakest spot in the side of the butte and burst out, creating a new path. You can see this breach in Lava Butte directly in front of you.
A’a or Pahoehoe?
In Hawai’i, lava flows are described as pahoehoe or a’a. These two descriptive terms explain how the surfaces of basaltic flows appear after lava cools. These terms have been adopted by scientists to describe not only this aspect of geology, but to also characterize how lava “behaves” as it flows from a vent. A smooth, ropy surface is typical of a pahoehoe flow when the lava oozes out like thick syrup, surrounding trees and burning them out. Thea’a flow you are standing on acts more like a molten bulldozer, knocking down everything in sight.
Lava Spreads Across the Land
Lava spread over 8 miles from here, flowing toward the present day city of Bend, and it is up to 100 feet deep in some places. These enormous pulses of lava have left behind enough basalt to build a four lane highway around the 6 times! You can get a good sense of this from the view at the Lava Butte overlook.
A Change in the Flow
Though it may have began as a fluid pahoehoe flow, it then transitioned into a traditional a’a flow, burying the landscape under an advancing front. It you look to your right you can see evidence that may support the theory of this flow starting off as a pahoehoe flow. Look for a piece of rock that looks like bent fingers.
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