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Ph.D. Research

I am working to develop a record of hurricane and large storm activity for southern New England and the Boston over the last millennium based primarily on the varved sedimentary record from a coastal lake outside of Boston.  Here's the text from a recent abstract that provides some details.

    A high resolution record of hurricane and tropical storm activity for the Boston area is being developed based on the 1,200 year long varved sedimentary record archived in the Lower Mystic Lake. The Mystic Lake is a low elevation (1 m above sea level), meromictic coastal lake directly connected to Boston Harbor by the Mystic River. Large overwash and storm surge events that drove inland of Boston Harbor delivered marine water to this normally fresh water basin, and these events can be detected by changes in sedimentology (turbidite/detritus layers) and diatom assemblages which indicate marine influence. A varve chronology based on counts from petrographic thin-sections and X-ray densitometry measurements has been developed, and shows excellent agreement with radiocarbon analyses.  Additional work to further confirm its validity by other radiometric means is in progress.  In conjunction with the varve chronology, event strata in the sedimentary record will be compared with the chronology of known storms during the historical period to calibrate and verify the record.  The Mystic Lake record will be compared with a 1 cm resolution loss-on-ignition record developed from Belle Isle Marsh in Boston Harbor.  Such marsh records are more typical of studies from other localities which reconstruct past hurricane frequency based on the presence of siliciclastic overwash layers in coastal stratigraphy. The comparison will allow us to determine how accurately both types of records serve as proxies for overwash and storm surge events. The frequency of hurricane events will be placed in the context of long-term climate changes, and may shed light on how hurricane frequencies might be expected to vary under globally warmer conditions in the future.

From left to right, here are descriptions for the five figures below.  Clicking a thumbnail will bring up a larger version.

  1. 15' topo map of Boston area from 1903; the Upper and Lower Mystic Lakes can be seen between Winchester, Medford, and Arlington; the huge increase in urbanization over the last century is clear when comparing this map to the recent air photo of the Mystic Lake/River system at the right
  2. a recent airphoto of the Mystic Lake/River system; tidal circulation up and down the Mystic River made it to some point past Cradock Dam in Medford during normal circulation, but not as far as the lake; as early as the 1850/60's it was known the lake was chemically stratified, and this was attributed to "occasional and rare...supplies of sea water"
  3. a 6 cm segment of laminated sediment viewed under plain transmitted and polarized light as a petrographic thin-section, and by X-ray exposure of a 2 mm thick sediment slab (top to left); preliminary varve counts can be seen on the thin-section images
  4. a poster presented at the Geological Society of America National Meeting held in Boston in November 2001
  5. a poster presented at the "Image Analysis, Sediments and Paleoenvironments Workshop" organized by P. Francus, R. Bradley, and J. Thurow, and held at UMass Amherst on 8-10 November 2001
     

As I have time, I'll add more figures and images to this page to provide additional details.