Page 111 - (DK) Ocean - The Definitive Visual Guide

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ATLANTIC OCEAN NORTHEAST coast, carried by wind (sand drift) ATLANTIC OCEAN NORTHEAST
and wave erosion. In some areas, CHESIL BANK
North Jutland Dunes attempts have been made to restrict Chesil Beach The bank is about 560 ft (170 m) wide and
this dune drift, to prevent sand from 50 ft (15 m) high along its entire length.
TYPE Coastal dunes inundating summer houses. Some TYPE Storm beach on The beach (left) is on its seaward side.
COMPOSITION Yellow early attempts were fruitless. For tombolo
sand, marram grass example, sand fences were built COMPOSITION Gravel of
LENGTH 155 miles into the dunes during World War II, flint and chert
(250 km) but the dunes have since moved LENGTH 18 miles (29 km)
behind them, leaving the fences on
LOCATION North and northwest coast of Jutland, the beach. More recently, many LOCATION West of Weymouth, Dorset, southern
Denmark dune areas have been stabilized England
more successfully by planting with
Much of the northern coastline of grasses and conifer trees. Chesil Beach forms the seaward side
Denmark’s Jutland Peninsula consists of the Chesil Bank, a remarkably long,
of sand dunes, which cover several SHIFTING SANDS narrow bank of sedimentary material
thousand square miles of coast. These Many sand dunes on the peninsula have that connects the coast of Dorset in
dunes are “active” in that they have a marram grass growing in them, which southern England to the Isle of
natural tendency to migrate along the helps constrain their movement. Portland. Behind the bank is a tidal
lagoon called the Fleet. Running
parallel to the coast, Chesil Bank looks
like a barrier island. However, because
it connects the mainland to an island,
it is classified as a tombolo. How
Chesil Bank and its beach originally
formed is debated—the most widely
accepted theory is that it originally
formed offshore and was then
gradually moved to its current
location by waves and tides.
The beach is classified as a
storm beach, as it is affected
by strong waves because it
faces southwest toward the
Atlantic and the prevailing
winds. Like most storm
beaches, it is steep,
with a gradient of
up to 45 degrees,
and is made
common where cliffs made of of gravel.
ATLANTIC OCEAN NORTHEAST
different types of rock are subject
Porthcurno Beach to strong wave action. Rock that is
especially hard and resistant to erosion
TYPE Pocket beach forms headlands, while intervening
COMPOSITION areas of softer rock are worn down
Yellow-white sand, to form pocket beaches. Unlike other
composed mainly of beaches, pocket beaches exchange
shell fragments
little or no sand or other sediment
LENGTH 500 ft (150 m) with the adjacent shoreline, because
LOCATION Southwest of Penzance, Cornwall, the headlands prevent longshore drift.
southwestern England, UK The sea at Porthcurno is a distinctive
turquoise, possibly due to the
Porthcurno is a typical pocket beach reflective qualities of the sand, which
located near Land’s End at England’s is made mainly of shell fragments.
southwesternmost tip. Like all pocket
beaches, it nestles between two GRANITE HEADLANDS
headlands that protect the sandy cove The headlands on either side
from erosion by winter storms and of the beach are formed from
strong currents. Pocket beaches are 300- million-year-old granite.
DISCOVERY
GRADED PEBBLES

Chesil Beach’s pebbles change
in size progressively from potato-
sized at one end to pea-sized
at the other. This reveals the
differences in wave energy along
its length—at one end, strong
waves wash smaller pebbles OCEAN ENVIRONMENTS
offshore; at the other, weaker
waves wash them onshore.