| Visit the woods of the Lost Creek Nature Trail, where an eruption of Mt. Hood swallowed up an entire old-growth forest. Stroll among the relics of this ancient forest and see those that have been buried and preserved by the mudflows, and newly uncovered by the waters of Lost and Cast Creeks. |
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Lost Creek sits inside the Old Maid Flat area of Mt. Hood National Forest at an elevation of about 2,600 feet. The Old Maid Flat area is named from one of the largest pyroclastic volcanic mudflows from Mt. Hood's "Old Maid" eruption that happened between 1760 and 1810 (most estimates put it in 1781 or 1782). You will notice two distinct landscapes here: (1) a newer area of lodgepole pine and mossy undergrowth, and (2) an older thriving area of forest with large trees and plentiful undergrowth. Lodgepole pine are native of eastern Oregon's gravel slopes and the coast's oceanfront well-drained dunes. These trees thrive on disturbance, and are the only trees that can survive in the gravel-laden, ash-rich soils along the Sandy River basin.
The eruptions that happened during this time are actually the most recent. There are three significant eruptive periods that have occurred at Mt. Hood. The Timberline eruptive period occurred about 1400 years BP (years are actually BP - Before Present - before 1950), the Zigzag period about 400 years BP, and the most recent - Old Maid eruptive period. Deposits from the Old Maid period can be found from the upper Sandy basin downstream to below the confluence of the Sandy and Salmon rivers near Brightwood. The eruption originated in the modern crater of Mt. Hood, where sulfur fumes still rise from the vents known as the Devil's Kitchen.
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The massive 800-foot volcanic dome is just 200 years old and formed during these eruptions. Two types of debris flow swept down the southern slopes of Mt. Hood during this time: the most destructive were the pyroclastic flows (fluid mixture of hot rock fragments, ash and gasses), which many of us are familiar with from the colossal Mount St. Helens eruption of May 18, 1980. In addition to these hot flows, cooler mudflows from flash-melted glaciers and snowfields also swept down Mt. Hood’s south slopes during the Old Maid events. The buried forests at the bottom of White River Canyon fell victim to these mudflows, as pyroclastic flows would have instantly incinerated the standing timber. Instead, the cooler debris flows simply knocked the forests over, and buried them under layers of mud and debris.
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Six prehistoric buried forests have been discovered at Mt. Hood to date. This area is the most extensive, and the trees in this part of the buried forest are exposed, for the most part, in the bed or near the banks of Lost Creek. Constant saturation by the waters of Lost Creek have kept portions of the trunks in a good state of preservation.
In November of 1805 and April of 1806 Lewis and Clark explored a river they named "Quicksand River". Captain Clark described it as follows in his journal: "...I arrived at the entrence of a river which appeared to scatter over a sandbar, the bottom of which I could see quit across and did not appear to be 4 inches deep in any part; I attempted to wade this stream and to my astonishment found the bottom a quick sand and impassible..." The name of this river was shortened in later years to the Sandy River. The expedition appears to have arrived while the river was still flushing the sediment of the Old Maid event through the system (they appeared to have arrived within 5 to 10 years of the event).
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Look around you. You might be confused thinking some of the stumps around you are more modern. This is because early inhabitants of this area saw the stumps as easy access to standing firewood or shake bolts. How can you tell the stump you are looking at is a remnant of the Old Maid eruption? Run your hand along the trunk and follow it below the ground surface. A modern tree is rooted at the surface and it will immediately break into roots.
This EarthCache will take you along the Lost Creek Nature Trail. Built by volunteers in 1972, it was designed to offer visitors a quality outdoor experience while encountering minimum obstacles. The trail is 0.5 miles long, is dotted with benches, informative signs, and is mostly wheelchair accessible.
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In order to log this Earthcache, you will need to read this page, check out some of the references, walk the Lost Creek Nature Trail at the cache coordinates and answer the following questions in an email to the cache owner:
| 1. Old Maid Flats came from one type of volcanic hazard that is a result of the pyroclastic flows and bursts: a fast moving slurry of rock, mud and water. What are these are called? |
| 2. Standing at the beaver pond, you can see two distinct types of forest. What do you see different about the forest on either side? Why do you think these two are side-by-side like this so deep in the forest? |
| 3. Given what you learned here about the "Old Maid" eruption, how does this differ from the volcanic eruption of Mt. St. Helens in 1980? |
| 4. What is a "relic tree"? Why are these trees still standing when the eruption of Mt. St. Helens knocked over all trees in its path? If you see a relic tree here, post a photo of it in your log. (Photo not required to log cache.) |
| 5. Finally, what is the middle name of the person to whom the picnic area is dedicated? Place this name on the passport if you are working on the CCHS GEO-Heritage Tour geocoin. |
And lastly, if you'd like, please post any others your favorite photos from the areas of this Earthcache.
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References:
In Search of Ancient Oregon by Ellen Morris Bishop
Post-GlaciaL Lahars of the Sandy River Basin, Mount Hood, Oregon
WyEast Blog: White River Buried Forest
Mount Hood—History and Hazards of Oregon's Most Recently Active Volcano
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