SUBFOSSIL FOREST AT NELLIE JUAN GLACIER

1. This large tree was killed, pushed over and buried by the most recent advance of Nellie Juan Glacier. The roots are intact and fragments of bark can still be found on the trunk; many of the subfossil logs in this area have similar levels of excellent preservation. Tree-ring cross-dating shows that this tree germinated before 1068 and was killed in 1592, and so was over 524 years old when it died.

Scroll down through this page or click on the map below to see more subfossil logs from the medieval old growth forest at Nellie Juan Glacier. Each red number links to a photo.

2. Aerial view of the gully where we collected most of our samples. Snowmelt from the pond in the background is cascading down and eroding through a terrace of till and kame deposits. Many logs in the central section of the gully are still in growth position or remain buried in the glacial deposits where they have been preserved for over 400 years. Additional logs were found scattered over the fan delta (foreground) that has prograded out into Nellie Juan lagoon in the 30 years since this site was deglaciated.

3. Large tree stump in growth position with a second log lying on the surface immediately upslope. The vertical exposures in the background are till and kame sediments that were deposited over the site.

4. Digging down at the base of the stump shown in the previous photo reveals the roots, confirming that this subfossil tree is still in its original growth position. Some bark is also preserved in this lower section of the stump.

5. Jim is standing at the roots of a large subfossil log with a second large log immediately behind him. Buried in and among the boulders in this view are a further six logs. Erosion by the stream in this location has removed all the gravel, sand and finer sediment, leaving just these large boulders as a lag deposit.

6. Dave with another stump still in its original growth position. Tree-ring cross-dating shows that this tree was alive here from at least 1171 to 1587. Unfortunately, bark could not be located on this particular tree and so the date of 1587 is probably an underestimate of when Nellie Juan Glacier advanced over and killed this particular tree.

7. View up the gully. An in situ stump is visible in the foreground and several large logs are upstream of Jim. The gray cliffs in the background are some of the till and kame deposits that were deposited over this site by Nellie Juan Glacier.

Dave collecting a core sample from a subfossil log. The increment borer cuts a pencil-thick core from the bark to the pith of the tree. Back in the lab this core is used to measure the tree-ring-widths and then to provide a tree-ring cross-date of the tree. Two to six cores were collected from each subfossil log used in this study.

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