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Stop 28, Lake Combie Complex: The Setting

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Stop 28 is in the low Sierra foothills at 38°59.034´N, 121°00.366´W and exposes pillow lavas of yet another ophiolite complex. (more below)
Our first pillow lavas
Photo (c) 2006 Andrew Alden, licensed to About.com (fair use policy)
The Lake Combie ophiolite is considered of early Mesozoic age (250–190 Ma), older than the Smartville complex we saw at stop 11 but possibly the same age as the Jarbo Gap ophiolite at stops 12 and 13. Here the seafloor basalt formations called pillow lavas (or lava pillows) are well exposed. These form along the deep-sea spreading ridges, where they have been filmed in the process of formation. See a gallery of pillow lavas with examples spanning 400 million years. There is no surer evidence of oceanic crust and its long-distance transport by plate motions.

This stop is the last of day 3. Day 4 is back in the San Francisco Bay area.

Day 1, Coast Range: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9

Day 2, Sierra Nevada: 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18

Day 3, Sierra Nevada: 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28

Day 4, Coast Range: 29 | 30 | 31 | 32 | 33

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