Partly as reconnaissance for a possible project next year, yesterday we climbed down into "Spring 3". This orange mud hole is where a group of students on the first year, put the final nail in the coffin for the hot spring hypothesis but had quite an adventure getting out. It is just as slippy and steep today.
Anyway, We found ash layers (weathered to white clays) in the main orange clay sequence:
The hole is quite dark, so the flash doesn't really do the layers much justice. The lower layer is where the pen knife is located and is a mix of reddish clay and white clay clasts. The upper layer is near the top of the picture. We cannot be sure which layer refers to which eruption without radioisotope dating, but the top one is probably the 1400 eruption, and the lower is the 1020-30 eruption. The left of the 1400 layer is also split - this is probably post-depositional (eg. slumping of loose sediments) although it is tempting to invoke the much smaller 1440 eruption.
The brown soils on the left are younger soils, similar to the top soil. This appears to have been an old erosion channel that was cut after 1400, but has since infilled. It (along with the older orange clays) are now being eroded by surface washouts. The reforestation efforts at Leaves and Lizards are already making such washouts rare.
So I have some reading to do, but we might have the subject for a volcano-sediment project for next year's class?
Anyway, We found ash layers (weathered to white clays) in the main orange clay sequence:
The hole is quite dark, so the flash doesn't really do the layers much justice. The lower layer is where the pen knife is located and is a mix of reddish clay and white clay clasts. The upper layer is near the top of the picture. We cannot be sure which layer refers to which eruption without radioisotope dating, but the top one is probably the 1400 eruption, and the lower is the 1020-30 eruption. The left of the 1400 layer is also split - this is probably post-depositional (eg. slumping of loose sediments) although it is tempting to invoke the much smaller 1440 eruption.
The brown soils on the left are younger soils, similar to the top soil. This appears to have been an old erosion channel that was cut after 1400, but has since infilled. It (along with the older orange clays) are now being eroded by surface washouts. The reforestation efforts at Leaves and Lizards are already making such washouts rare.
So I have some reading to do, but we might have the subject for a volcano-sediment project for next year's class?
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