Lava Cast Forest, Oregon
Posted by: Groundspeak Premium Member Volcanoguy
N 43° 48.859 W 121° 17.102
10T E 637924 N 4852679
Quick Description: The Lava Cast Forest area of Newberry National Volcanic Monument.
Location: Oregon, United States
Date Posted: 7/1/2007 4:54:53 PM
Waymark Code: WM1RFX
Published By: Groundspeak Premium Member Blue J Wenatchee
Views: 125

Long Description:

From the parking area for the Lava Cast Forest, a Recreation Fee Site requiring a parking pass, follow the Lava Cast Forest Trail to the waymark. Lava Cast Forest is a major point of interest in Newberry National Volcanic Monument. The area is usually accessible from mid-May to mid-November.

This area was discovered by Walter Perry of the Forest Service in 1925. The former Lava Cast Forest Geological Area was established by the Forest Service in 1942 and is now a part of Newberry National Volcanic Monument. The name of the area is based on the many lava trees and tree molds in the area, but the name is incorrect because a mold is formed around an object whereas a cast fills a mold. So actually the name should be "Lava Mold Forest".

Lava trees and tree molds are formed when lava enters a forested area. As fluid pahoehoe lava surrounds a living tree, a crust of solidified lava forms around the tree due to the moisture in the tree causing cooling of the lava surface. The tree typically burns out to leave a vertical, open tree mold. If the level of the flow drops, a collar of lava may project above the final surface to indicate the high stand of the flow. These collars of lava are referred to as lava trees. When the tree burns through at flow level, the upper part of the tree may fall into the lava and become coated with lava to form horizontal tree molds. Horizontal tree molds also form when trees are pushed over in the high velocity deeper rivers of lava and are held in place by their roots. Vertical tree molds typically only form where flow velocity is low.

Carbon-14 age-dates for eruptions along the NW Rift Zone of Newberry Volcano range from 5800 to 6400 C-14 years.

Carbon-14 age-dates must be corrected to give calendar or actual year age-dates. Primarily because the production of C-14 in the atmosphere by cosmic rays is not uniform through time, age-dates derived from C-14 must be calibrated with known dates. Conversion from C-14 to calendar years is now possible throughout the range of 0 to 11,390 calendar years ago based on tree ring chronologies and other methods allow corrections back to almost 22,000 calendar years. C-14 age-dates are always referenced to the year 1950 A.D. Calendar year age-dates are likewise referenced to 1950.

The corrected ages for eruptions along the NW Rift Zone range from 6600 to 7200 years.

Tree molds in the basalt flows of Newberry Volcano have been a frequent source of charcoal for C-14 dating. This source of charcoal is one reason for the 600-year spread in C-14 dates. To obtain the best possible date on a flow the charcoal should be from the outermost rings of a tree, but in a large three to four-foot-diameter tree mold the remaining charcoal could easily have come from the interior of a large pine that was 400 years old, therefore the resulting C-14 date could be 400 years to old.

The corrected age that is most often used for the NW Rift Zone eruptions is 7000 calendar years.

Along the Lava Cast Forest Trail are 12 numbered posts that are described in a brochure usually available at the trailhead. Information from the brochure is include below:
#1 - The large ponderosa pine before you is about 300 years old. Under ordinary living conditions, ponderosas can live 300-350 years. Compare size, height, and general appearance to those trees out on the flow. All trees are approximately the same age.
#2 - Hot molten lava flowed through the pine forest, surrounding or covering most existing life in its path. Present plants, rooted in wind-deposited ash, demonstrate nature’s ability to revegetate the lava flow area.
#3 - Wild currant, rock penstemon, and Indian paintbrush are common residents of this arid climate. Visit Lava Cast Forest in early summer when the purple penstemon and red-orange paintbrush combine with the black rock to create a sight to stir the human spirit.
#4 - Liquid pahoehoe lava poured out of a series of vents beyond the tree line. Supply exceeded drainage, and a large lake formed where you now stand. As the eruption subsided, downflow drainage occurred, decreasing the lake depth to 10-15 feet.
#5 - A downed tree has lost its struggle for survival. In death as in life, it is useful as a refuge, food, and “Animal Inn” to animals, birds, and insects. The wood gradually decays and assists in making new soil which will support a future forest.
#6 - Tree molds were formed as lava spilled through the pine forest, flowing against the upstream side of the tree trunks. Lava Cast Forest derives its name from the concentration of these features. A more accurate explanation, however, defines a cast as having filled a mold, while a mold is formed around an object such as a tree.
#7 - Proof that two trees once grew together remains in the half-molds. Generally, the open side faces downhill and indicates lava flow direction. The holes extend 10 to15 feet under the lava into soil which once supported the vanished forest.
#8 - Three trees came from this single stump. The holes join at the base.
#9 - Fissures containing a series of vents extend almost seven miles in a northwesterly direction. This line of weakness in the earth’s crust originates at East Lake in the caldera of Newberry Volcano. At this trail stop, Newberry Volcano occupies the entire skyline. Fissures should not be confused with cooling cracks clearly visible from here.
#10 - When lava surged through the stands of pine, some trees were pushed over by its force. Trees that were snapped off were carried away. Others remained, anchored by their roots. Horizontal molds show this feature.
#11 - From this rock rim, notice an isolated forested island, or “kipuka”, surrounded by an expansive sea of lava. The island contains a cluster of much older cinder cones completely encircled by the younger lava. Your rocky perch is also a remnant of an older lava flow.
#12 - During flood stage, the lava current moved a clump of trees to where you see the jumbled pattern in the mold at this site. Lava, reheated by the burning trees, dribbled into the space between the original mold and charred wood. This pattern is often mistaken for bark impressions.

Waymark is confirmed to be publicly accessible: yes

Parking Coordinates: N 43° 49.050 W 121° 17.340

Access fee (In local currency): 5.00

Requires a high clearance vehicle to visit.: no

Requires 4x4 vehicle to visit.: no

Public Transport available: no

Website reference: Not listed

Visit Instructions:
No specific requirements, just have fun visiting the waymark.
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