136
The Last Resource
the contours of the sea oor is an important factor in both coastal
erosion and the transport of material along the shore. During the
Second World War the system was used in reverse: by studying
aerial photographs of the refraction of waves along enemy coast—
lines, scientists were able to determine the underwater topography
in preparation for amphibious assaults.
The energy brought to bear on the shore by breaking waves is
tremendous. At Tillamook Rock, Oregon, which suers frequent
storms, the lighthouse beacon has to be protected by a heavy steel
grating from ying rock—and this beacon stands 139 feet above low
water! One frequently quoted story about the destructive energy of
the sea concerns the breakwater at Wick in Scotland. During storms
in December 1872, the designer of the breakwater was amazed to
see this massive structure weighing some 1,350 tons moved bodily
into the anchorage it was supposed to protect. He rebuilt the break—
water making it twice as heavy, but ve years later this improved
design suffered a similar fate from waves which must have been
exerting a pressure of some 6,340 pounds per square foot! But
violent storm waves are not the only ones with inuence on the
coast. At Covehithe on the east coast of England for example, the
land is being eroded slowly but steadily at a rate of about 17 feet a
year by wave action.
Many shorelines remain apparently unchanged because equi—
librium has been reached between destructive and reconstructive
forces. Therefore the removal of, say, gravel or the incorrect siting
of a breakwater can have far—reaching consequences. Take the case
of the little Devon village of Hallsands in south—west England. In
1897 dredging was begun offshore to provide shingle for harbour
works at Plymouth. The removal of this material interfered with the
maintenance of the beach at the shing village of Hallsands. By
1902 the beach had been lowered by 12 feet. Dredging was stopped,
but storm waves were already attacking the village and by 1917 only
a few ruined cottages remained.
The discussion so far has been couched solely in terms of simple
waves, but While this suices to explain the basic processes, it is
completely inadequate as et description of the state of the sea. There
is no such thing as a simple ocean wave: waves are the product of
many different interacting forces (see gure 14). To sort out the
resulting confusion, the scientist has to fall back on statistical
analysis which in turn requires vast amounts of information. Various
The Last Resource
the contours of the sea oor is an important factor in both coastal
erosion and the transport of material along the shore. During the
Second World War the system was used in reverse: by studying
aerial photographs of the refraction of waves along enemy coast—
lines, scientists were able to determine the underwater topography
in preparation for amphibious assaults.
The energy brought to bear on the shore by breaking waves is
tremendous. At Tillamook Rock, Oregon, which suers frequent
storms, the lighthouse beacon has to be protected by a heavy steel
grating from ying rock—and this beacon stands 139 feet above low
water! One frequently quoted story about the destructive energy of
the sea concerns the breakwater at Wick in Scotland. During storms
in December 1872, the designer of the breakwater was amazed to
see this massive structure weighing some 1,350 tons moved bodily
into the anchorage it was supposed to protect. He rebuilt the break—
water making it twice as heavy, but ve years later this improved
design suffered a similar fate from waves which must have been
exerting a pressure of some 6,340 pounds per square foot! But
violent storm waves are not the only ones with inuence on the
coast. At Covehithe on the east coast of England for example, the
land is being eroded slowly but steadily at a rate of about 17 feet a
year by wave action.
Many shorelines remain apparently unchanged because equi—
librium has been reached between destructive and reconstructive
forces. Therefore the removal of, say, gravel or the incorrect siting
of a breakwater can have far—reaching consequences. Take the case
of the little Devon village of Hallsands in south—west England. In
1897 dredging was begun offshore to provide shingle for harbour
works at Plymouth. The removal of this material interfered with the
maintenance of the beach at the shing village of Hallsands. By
1902 the beach had been lowered by 12 feet. Dredging was stopped,
but storm waves were already attacking the village and by 1917 only
a few ruined cottages remained.
The discussion so far has been couched solely in terms of simple
waves, but While this suices to explain the basic processes, it is
completely inadequate as et description of the state of the sea. There
is no such thing as a simple ocean wave: waves are the product of
many different interacting forces (see gure 14). To sort out the
resulting confusion, the scientist has to fall back on statistical
analysis which in turn requires vast amounts of information. Various