![]() ![]() Molten lava on this scale would have instantly vaporized the Middle Fork as it flowed down valley. Here, a lobe of lava pushed laterally (left) and uphill into the side canyon of Bear Creek, permanently diverting the Middle Fork Hood River in the process. The oversteepened slopes along the west margin of the stream (shown as a distinct shadow) are the result of the Middle Fork continuing to cut away at the base of Blue Ridge, some 7,000 years after the lava flow formed.Īnother view of the mid-section of the Parkdale flow (Map C, below) shows fascinating features along the west margin of the formation. The view in Map B, above, also shows how the Parkdale flow pushed the Middle Fork Hood River against the foot of Blue Ridge, to the west. This view also shows the first lateral lobes, splitting off the main flow as the molten lava reached the open floor of the Upper Hood River Valley, and where the volume of lava overtopped or burst through the levees along the main channel. This main channel also has well defined levees of solidified lava along its margins, a common feature on the more liquid Pahoehoe (pronounced pa-HOI-hoi) form of lava, but less so with the viscous A’a’ lava that makes up the Parkdale formation. ![]() Moving south to the middle of the Parkdale flow (Map B, below), the LIDAR image shows a powerful, quarter-mile wide stream of lava pushing down a channel at the center of the flow. Below the flow, the flood area averages about one-third mile in width, but where the channel along the west side of the lava flow, it measures only a out one-tenth of a mile in width. In this lowest extent of the flow, it’s also clear that the lava covered most of the Middle Fork flood plain. The gentle slope of the open valley floor was responsible for the broad toe of the lava flow, which spread out in the shape of a hand (or paw?) once it emerged from the confining canyon walls of the Middle Fork canyon. Though the flow was generally heading downhill (the underlying valley floor drops about 250 feet per mile in this area), LIDAR shows it was spreading out, too, as evidenced in the many secondary lobes that formed at the terminus of the flow. Starting on the north end, at the toe of the Parkdale flow (Map A, below), the LIDAR imagery reveals the flow lines in the once-molten rock in great detail, when compared to traditional maps and air photos. The LIDAR imagery beautifully illustrates these characteristics of an A’a’ flow, including the tall, steep edges of the flow that result from this dense, slow-moving form of lava. This floating skin of jagged, solidified rocks echoes the movement of the underlying flow, thus creating the flow lines. ![]() The Parkdale lava is of the A’a’ variety (pronounced “ah-ah”), characterized by a thick, pasty molten core carrying hardened chunks of cooled lava on its surface like a crusty skin. (for a larger LIDAR view of the entire flow, click here) This article focuses on the Parkdale Lava Flow, one of the formations where LIDAR offers an especially striking new look at the geologic story.įour sections of the Parkdale flow (shown on the index map, below) are the focus of the article. 21.The new LIDAR data viewer created by Oregon’s Department of Geology and Mineral Industries (DOGAMI) offers a fascinating new look at familiar features in the Mount Hood region. No guarantee, warranty or representation of any kind is made regarding the completeness or accuracy of descriptions or measurements (including square footage measurements and property condition), such should be independently verified, and Compass expressly disclaims any liability in connection therewith. and/or other countries.Ĭorporate Responsibility, Privacy & Legal Notices: Compass is a licensed real estate broker, licensed to do business as Compass RE in Delaware, Idaho, New Jersey, Pennsylvania and Tennessee, Compass Real Estate in Washington, DC, Wyoming and Idaho, Compass Realty Group in Missouri and Kansas, and Compass South Carolina LLC in South Carolina. Do Not Sell or Share My Personal Information, Terms of Service, Privacy Center, Scam Avoidance, Responsible Disclosure, Compass is an E-Verify employer, Notice for California Applicants, California COVID-19 Rules of Entry, and Your CA Privacy RightsĬOMPASS, the Compass logo, and other various trademarks, logos, designs, and slogans are the registered and unregistered trademarks of Compass, Inc. ![]()
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