Wednesday, November 28, 2012

Basaltic Lava Pillows - Pillow Basalts

Images, video and map describe pillow basalt (pillow lava) formation and location within the Columbia River Basalt Group. Additional photos below show examples of contact between pillows and palagonite.
Nick Zentner and I have been trying to figure out a few of the buttons on a video camera and how to hold a long pole with a fuzzy mic so we can film 2 Minute Geology videos.
One of our first episodes is embedded midway through this blog post.

Geologist Nick Zentner describes pillow lavas.
Nick describes lava flowing into ancient lake near Vantage, WA.
Pillow lavas form when basaltic lava encounters water. Active pillows have been video recorded in Hawaii as the ongoing Kilauea eruption sends active basalt lava flows into the Pacific Ocean. In continental settings, pillows are formed when flood basalts bury landscapes dominated by large freshwater lakes and streams.
The Columbia River Basalt Group of Washington and Oregon (USA) is a stack of more than 300 individual lava flows. The flows issued forth from deep fissures that began forming 17 million years ago in southeast Washington and northeast Oregon. Some of the flows have well-developed pillow structures in the basal sections - which proves the existence of lakes between eruptions. Thousands of years are estimated between eruptions of basalt lava from the fissures.

Pillow basalt exposure near Interstate 90 bridge at Vantage, WA.
I-90 Bridge at Vantage, WA

This episode begins with Nick standing in Sand Hollow (47,15033-119.98147) at one of the region's most impressive Pillow Basalt road cuts - where Washington Route 26 begins its climb east out of the Columbia River Gorge near Vantage, WA. The Ginkgo and Sand Hollow basalt flows are featured - 15 million year old lavas. Lake Vantage existed 15 million years ago.

Pillow basalt in Columbia River Basalt Group.
Nick examines Columbia River Basalt Group pillows.

Nick Zentner provides detailed description of palagonite.
Palagonite explained at Potholes Coulee Location.
The episode then switches to Nick at the mouth of Potholes Coulee (47.15033-119.98147) southeast of Quincy, WA. Details within a pillow zone exposed by the Ice Age Floods are studied. Palagonite between the pillows proves to be a collection of small, angular blocks of volcanic glass (obsidian) which implies sudden, explosive events as the 2,000 degree lava encounters lake water.
Petrified logs on display in nearby Ginkgo Petrified Forest State Park have all been found within the palagonite zone in the base of the Ginkgo Flow. The water-logged logs escaped the incinerator of the Ginkgo Flow - and eventually became petrified as silica from the lava soaked into the wood.

New Pillow Basalt Video

Click video to play

Columbia River Basalt Group pillow basalt.
Click any image to expand.

Pillow basalt, photo by Nick Zentner. CWU Geology
Pillow basalt - Photo by Nick Zentner.
Love the Ellensburg cowboy hat for scale!

Pillow lavas detail.

Contact between pillow and palagonite.
Contact between pillow and palagonite - [above and below].

Volcanic glass within palagonite.
Volcanic glass within palagonite.

Palagonite band upper Grand Coulee.
Palagonite band - Grand Coulee rim.
Palagonite on Mars: Based on infrared spectroscopy, the fine-grained component of Mauna-Kea palagonite is the terrestrial material with the best match to the spectral properties of Martian dust, and is believed to be similar in composition and in origin to dusty component of the surface regolith of Mars. The spectroscopic signature of palagonitic alteration on Mars is used as evidence for the existence of water on Mars. -Wikipedia

Luke Foster inspects water stained pillow exposure in Potholes Coulee.
Luke inspects water-stained pillow structures in Potholes Coulee.

Multnomah Falls pillow basalt.
Many amazing pillow exposures are found in the Columbia Gorge. Including these pillows behind Multnomah Falls.
Sand Hollow pillow basalt exposure.
Use Google Maps navigational tools to explore the area.

1 comment:

BeyonceJustice said...

Quite interesting blog on Lava flow.
Lava Flow.