Wednesday, March 04, 2009
Of the class of 40 or so people here to learn about climate change, only half a dozen or so probably wandered down the 200 yards to the overlook at the bluff. The classroom at the Reserve is nice, but the shore is always better. The tide was out, exposing not just the narrow gravelly beach, but miles of tidal flats and matted eelgrass waiting to be floated by the next tide.
A couple interesting things illustrated by the photos. If you look carefully, you can see a gravelly fan extending out across the flats - this is typical wherever a small stream reaches the beach along here and at lower tides spreads the sand and gravel seaward. The tree shows how you can use vegetation (big straight-growing conifers, at least) to infer the history of bank stability. This tree suggests two episodes of instability - one, many decades ago, when a young tree collapsed and a branch took over vertical growth, and then a more recent event that caused the vertical trunk to tilt landwards as the roots slid. Or something like that.