HomeMy WebLinkAboutCMP Forum June 25, 2012 - Part 1_201401231628330607Nantucket Coastal
Processes
Rebecca Haney, Coastal Geologist
MA Office of Coastal Zone
Management
June 25, 2012
•Massachusetts 21,000
to 18,000 years ago
•Throughout New
England there is a layer
of sediment ranging from
silt and clay to boulders
•Along the coast the finer
grained material is
removed first, coarser
material is left behind
Glacial History
From: Brownlow, A.H., Ed. 1979. Cape Cod
Environmental Atlas. After Strahler, 1966
Sediment supply & coastal banks
Coastal Banks provide a sediment supply,
act as a vertical buffer, or both
Longshore sediment transport
1.Oblique wave approach causes ‘zigzag’ pattern of
sediment along the beach (“River of Sand”)
2.Changing the size of sediment on the beach can alter
transport patterns
3.Altering the coast with hardened structures can have
negative impacts
Across-shore sediment transport
Waves transfer energy,
not water
1.Energy must be dissipated/ has to go somewhere!
2.Waves roll up the beach, spread out/dissipate energy
3.Alter the bottom (beach scraping, dredging, etc) and
the nature of the incoming wave energy changes
Resources
•CZM website: mass.gov/czm
•Against the Tide,by Cornelia Dean