65
in fourteenth century England. There are slightly varying definitions but, basically,
if there are several competing theories that make exactly the same predictions, the
simplest one is the better. So, storms were more likely the perpetrators and the barrier islands the victims. Several strong hurricanes have hit the Outer Banks over the
past century and caused overwash and the opening of, usually, ephemeral inlets.
These inlets do not allow for the colonization of Pamlico Sound by benthic forams
from the shelf. We need an event or events of much greater magnitude that destroy
large segments of barrier island and allow eddies of Gulf Stream waters to be
advected into the Sound by southerly prevailing winds (Fig. 4.10).
My mind, for some reason, returned to my family’s miserable experience of
five months trapped in a hotel room due to a set of three hurricanes in just several
weeks that physically cut off Greenville from the rest of civilization and delayed our
purchase of a house. Perhaps a series of very powerful hurricanes traveled up the
Gulf Stream a thousand or so years ago and impacted the Outer Banks but, as our
data suggest, the southern portion in particular. These must have been extremely
powerful storms because their effects were long-lasting. We radiocarbon dated the
base of the suspect sand unit using 1000 specimens of a single species of the benthic
foram, Elphidium excavatum, that were clearly in situ because specimens ranged
from tiny juveniles to full-grown adults (Fig. 4.9). Thus, no transport, sorting and
redeposition of shells had occurred.
The estimated age was approximately 1200 years before present. The top of the
sand unit and, hence, the return to the deposition of mud in a sound protected from
the ocean by reformed Outer Banks barrier islands, had an age of approximately
500 years before present. Thus, the segmentation of the barrier islands lasted some
700 years. When the first European visitors arrived in 1585 the map produced by
John White showed that the Outer Banks had many more inlets than exist today (see
Mallinson’s chapter). The barriers islands had healed somewhat, but evidence of
segmentation persisted in these several inlets.
Why would such strong and devastating hurricanes occur 1200 years ago? This
was the time of the Medieval Climate Anomaly, a period of time lasting a few hundred years when temperatures in the northern hemisphere were warmer than in preceding and succeeding years (the Medieval Climate Anomaly was followed by the
Little Ice Age). Warmer temperatures may not necessarily lead to more hurricanes,
but the work of several hurricane researchers suggests that warming can lead to
more intense hurricanes. That may well be what happened 1200 years ago.
The same scenario is relevant today. Mainly due to anthropogenic activities (the
burning of fossil fuels, for example) we are currently in a period of global warming
of a magnitude (so far) similar to the Medieval Climate Anomaly. The difference is
that the warming is happening much faster than 1200 years ago. Furthermore, as
described elsewhere in this book, (see the Kemp and Horton chapter) sea-level is
rising along the mid-Atlantic coast of the US faster than to the north or south due to
subsidence of the land. Current warming climate could well result in more hurricanes and, scarily, perhaps more intense hurricanes. Add perhaps 1 meter (3 ft. 3 in)
4 Barrier Island Breakdown: The Ephemeral Outer Banks of North Carolina
in fourteenth century England. There are slightly varying definitions but, basically,
if there are several competing theories that make exactly the same predictions, the
simplest one is the better. So, storms were more likely the perpetrators and the barrier islands the victims. Several strong hurricanes have hit the Outer Banks over the
past century and caused overwash and the opening of, usually, ephemeral inlets.
These inlets do not allow for the colonization of Pamlico Sound by benthic forams
from the shelf. We need an event or events of much greater magnitude that destroy
large segments of barrier island and allow eddies of Gulf Stream waters to be
advected into the Sound by southerly prevailing winds (Fig. 4.10).
My mind, for some reason, returned to my family’s miserable experience of
five months trapped in a hotel room due to a set of three hurricanes in just several
weeks that physically cut off Greenville from the rest of civilization and delayed our
purchase of a house. Perhaps a series of very powerful hurricanes traveled up the
Gulf Stream a thousand or so years ago and impacted the Outer Banks but, as our
data suggest, the southern portion in particular. These must have been extremely
powerful storms because their effects were long-lasting. We radiocarbon dated the
base of the suspect sand unit using 1000 specimens of a single species of the benthic
foram, Elphidium excavatum, that were clearly in situ because specimens ranged
from tiny juveniles to full-grown adults (Fig. 4.9). Thus, no transport, sorting and
redeposition of shells had occurred.
The estimated age was approximately 1200 years before present. The top of the
sand unit and, hence, the return to the deposition of mud in a sound protected from
the ocean by reformed Outer Banks barrier islands, had an age of approximately
500 years before present. Thus, the segmentation of the barrier islands lasted some
700 years. When the first European visitors arrived in 1585 the map produced by
John White showed that the Outer Banks had many more inlets than exist today (see
Mallinson’s chapter). The barriers islands had healed somewhat, but evidence of
segmentation persisted in these several inlets.
Why would such strong and devastating hurricanes occur 1200 years ago? This
was the time of the Medieval Climate Anomaly, a period of time lasting a few hundred years when temperatures in the northern hemisphere were warmer than in preceding and succeeding years (the Medieval Climate Anomaly was followed by the
Little Ice Age). Warmer temperatures may not necessarily lead to more hurricanes,
but the work of several hurricane researchers suggests that warming can lead to
more intense hurricanes. That may well be what happened 1200 years ago.
The same scenario is relevant today. Mainly due to anthropogenic activities (the
burning of fossil fuels, for example) we are currently in a period of global warming
of a magnitude (so far) similar to the Medieval Climate Anomaly. The difference is
that the warming is happening much faster than 1200 years ago. Furthermore, as
described elsewhere in this book, (see the Kemp and Horton chapter) sea-level is
rising along the mid-Atlantic coast of the US faster than to the north or south due to
subsidence of the land. Current warming climate could well result in more hurricanes and, scarily, perhaps more intense hurricanes. Add perhaps 1 meter (3 ft. 3 in)
4 Barrier Island Breakdown: The Ephemeral Outer Banks of North Carolina