Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Possible Tsunami Deposits on the Caribbean Coast of the Yucatán Peninsula

Charles E. Shaw and Larry Benson
Journal of Coastal Research
Vol. 31, No. 6 (November 2015), pp. 1306-1316
Stable URL: http://www.jstor.org/stable/43598460
Page Count: 11
  • Read Online (Free)
  • Download ($20.00)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
Preview not available

Abstract

The western Caribbean Basin is notable for its tectonic stability. It has experienced no historical earthquakes or the tsunami that sometimes accompany them. This paper describes a single, wedge-shaped, boulder-covered, coastal berm on the Yucatán coast of México that stretches unbroken for 50 km across a coastal segment characterized by rocky headlands that alternate with crescent beaches. The remainder of the 350 km of Yucatán coast consists mostly of mangrove that extends 1 to 30 km inland, often behind long, sandy beaches. On the headlands, the surface of the berm is densely paved with boulders—large boulders on its seaward face and smaller boulders and cobbles on its gently sloping inland surface. The top of the berm reaches an elevation >4 m, above the reach of all but the largest modern storm waves. Berm sediments on the headlands consist of two distinct layers of unbedded coarse sand with numerous randomly distributed boulders and cobbles in the lower layer and a crudely textured gravel and sand layer above. At first glance the two layers appear to be separated by 20 cm of white sand above a thin, discontinuous zone of dark, greyish sand that contains isolated balls and smears of black organic material, apparently derived from a soil, or possibly leaf litter. The berm and its associated boulders track the modern coastal morphology in precise detail as it follows the form of modern headlands, bays, and transcoastal channels, indicating that deposition took place after development of the present coast. The berm sediments record two or three large waves, depending on whether the wave that deposited the boulder pavement is regarded as part of the second wave or as a separate wave. Radiocarbon dating indicates that at least one wave struck the coast approximately 1500 years before present. Minimum wave run-up exceeds 4 m above present sea level, and inland inundation reached 400 m along bays and transcoastal channels. The position and elevation of the berm, its lack of well-developed internal bedding, the paving of the berm surface by thousands of boulders, and its 400-m extent inland along channels and bays are features commonly associated with tsunami. However, some recent studies conclude that all of the features listed also can be produced by mega-hurricanes. Placed in the context of our literature search of the recent history of hurricanes and tsunami in the Caribbean Basin, we conclude that the single berm on the Yucatán coast represents an anomalous event for this area and that the berm sediments bear a strong similarity to descriptions of sediments from some historical tsunami and are unlike sedimentary features associated with historical hurricanes.

Page Thumbnails

  • Thumbnail: Page 
[1306]
    [1306]
  • Thumbnail: Page 
1307
    1307
  • Thumbnail: Page 
1308
    1308
  • Thumbnail: Page 
1309
    1309
  • Thumbnail: Page 
1310
    1310
  • Thumbnail: Page 
1311
    1311
  • Thumbnail: Page 
1312
    1312
  • Thumbnail: Page 
1313
    1313
  • Thumbnail: Page 
1314
    1314
  • Thumbnail: Page 
1315
    1315
  • Thumbnail: Page 
1316
    1316