« AnteriorContinuar »
Coast of Cornwall.—From Hartland Point the coast for 15 miles trends south, and is bordered by rocky cliffs varying in height from 120 to 700 feet. The sea washes the foot of the cliffs except in some of the bays and indents. From Cleve iPoint to Bude there is a narrow strand under the cliffs. At Widemouth Bay the shore trends south-westerly to Tintagel Head, which rises 250 feet above the sea, and the coast continues steep and rocky to Pentire Head, which consists of greenstone and trap.
On the south side of this headland is the outlet of the river Camel, and the harbour of Padstow. A bar of sand and shingle stretches across the entrance to the river, and within the bar is an extensive tract of sand named Doom Bar.
The sand on the beach consists of comminuted sea-shells, principally mussels, and is largely used for manure, several thousand tons of this sand having been removed by the farmers for this purpose. In 1609 an Act was passed (7 Jas. L, c. xviii.) making it lawful for any person to take from the shores of the coast of Devon and Cornwall, below high water, the sea-sand "which by long trial and experience had been found very profitable for the bettering of land, especially for the increase of corn and tillage."
There are sand-hills consisting of shell-sand blown off the beach of considerable height, which have advanced inland, burying farms and houses and the church of St. Edenoch.
The coast from Trevose Head, on the south side of Padstow Bar, is rocky and precipitous, and much indented to Mawgan. At Constantino Bay, on the south side of Trevose Head, are hills of blown sand. In the recessed cliffs between Port Mawgan and New Quay in Watergate Bay, for upwards of 2 miles, is one of the few sand-beaches along this rocky coast.
Beyond New Quay the coast trends nearly due south, and is embayed between Towan Head and St. Agnes' Head, a hard slate rock, and in the embayment is Perran Bay, where the coast is bordered by a sandy strand and sand-hills. The Perran sandhills have been kept in check and prevented drifting inland by a river for 2 miles between Treamble and Holywell Bay. Much land has been covered in one place by the drifting of these sands, due principally to the stopping up of a small stream near Gear by mining operations.
The sands running over the low land behind Holywell Bay near Crantack were stopped by a streamlet near Tregal.
The old church of Peranzabuloe, which was at one time completely buried in the sand, became again uncovered by its drifting further inland.
South of St. Agnes' Head, which rises 617 feet, there is a narrow beach at the foot of the cliffs, which here run due south.
St. Ives' Bay, which lies deeply recessed between St. Ives' Head, composed of greenstone, and Godevry Head, a compact sandstone and slate cliff, is 3£ miles wide, and faces nearly north, the depth being 2 miles. The bottom of the harbour is covered with sand, and there is some shingle. The coast is composed of cliff-bound slopes. In the centre of the bay is an estuary which is the outlet of the river Hayle and several smaller streams. The sand-hills which border the bay cover several square miles, the sand consisting chiefly of broken shells.
From St. Ives the coast trends south-westerly to Cape Cornwall and the Land's End, and is rocky and much indented, the cliffs rising from 50 to 200 feet. Whitesand Bay is set back between these headlands, and faces nearly due west. The sand beach in this bay is also composed of broken sea-shells.
From the Land's End round to Mount's Bay the cliffs, composed of granite, are steep and rocky and washed by the sea. Mount's Bay lies between the Runnel Stone and Lizard Point, a distance of 18 miles, the bay facing south. It contains several minor bays and five harbours. On the western coast the cliffs are low and the shore is rugged, consisting of large masses of loose rock; the eastern cliffs consisting of igneous rocks and greenstone. Near Newlyn the cliffs rise to 40 feet, with a flat stony shore and a shingle beach. In Kynance Cove the red, green, grey, and yellow coloured serpentine cliff has become polished by the beating of the waves; the variegated colours of the cliff, and of the boulders at the foot, forming a striking contrast with the white sand of the beach.
The beach continues sandy to Penzance, which lies embayed, and between it and Newlyn the coast is wasting, the destruction having been very rapid during the last half-century. A wall has been erected to protect the road, which was in danger. The shingle-bank is 12 feet above the marshes at the back, and rests on clay, the top being 14 feet above high water. It is 20 yards distant from the line of ordinary high water. The pebbles are composed largely of quartz derived from the debris of the granite rocks in the bay, and have been worn down by the continual drift over 2 or 3 miles of shore, travelling to the eastern headland with westerly winds and to the opposite headland with easterly winds. On the other side of the headlands the shingle is of a different character. Below the shingle the beach is covered with fine sand for 33 yards to low water. There is also a bank of fine white sand, consisting of quartz, mica, and hornblende.
At the eastern end of Penzance Bay the cliffs at Marazion, consisting of Devonian slate, are continually wasting. The beach, which is half a mile wide, is covered with sand, and there is a bank of granitic sand.
St. Michael's Mount is an island joined by a low causeway one-third of a mile long to the land, and consists of an isolated mass of granite 195 feet high. It has been separated from the mainland by the wearing away by the sea of the softer slate rocks of which the cliffs consist.
The cliffs around Cuddon Point are high and precipitous, with several rocky ledges on the shore to Prussia Cove, where they decrease in height, and have a sandy strand. From Hoe Point eastwards the coast is low and a small bay is formed between two headlands, with a sandy beach called the Pray Sands, which extend 250 yards to low water. Beyond this the shore is bounded by heavy masses of loose rock.
From Port Leven the coast is low with a sandy beach, after which the cliffs rise to a height of 200 feet, the shore continuing sandy for some distance.
Near Helstone is a deep indent known as Loo Pool, the entrance to which is blocked by a bar of shingle, the top being 34 feet above low water, and 100 to 130 yards wide, completely stopping the outfall from the river Caher, and the water being ponded back, a large pool 173 acres in extent is formed. In wet weather, when the water rises 10 feet above the normal level, a narrow channel is cut through the shingle and the surplus water is let off. As soon as this is accomplished, the cutting fills up by the drifting shingle. The shingle extends to a depth of 150 feet below the surface of the land, and consists of pebbles derived from the debris of the neighbouring rocks, principally of quartz, granite, serpentine, and shale.
DESCRIPTION OF THE COASTS OF THE NORTH OF FRANCE, BELGIUM, AND HOLLAND—DESTRUCTION—LITTORAL DRIFT AND WORKS OF PROTECTION.
Cape Barfleur to Cape Antifer.—Cape Barfleur forms the western headland of the great bay of the Seine, Cape Antifer forming the eastern headland, the distance between the two being 55 miles, the greatest depth being 24 miles. This bay is open to all winds from north-west round by north to north-east. The flood tide sets into the bay and along the shore in a southeasterly and easterly direction till the Seine is reached, when one set of the tide is easterly into the estuary, and the other north-easterly some distance off the shore to Cape Antifer, when a counter-tide sets down the coast in a south-westerly direction, which, flowing round Cape la Heve, also enters the Seine. The rise of spring tides in the bay is from 18 to 22 feet.
The shores of the western side of the bay of the Seine are low and sandy, backed by sand-hills. Sixteen miles south-east of Cape Barfleur is the Bay of Grand Vay, and a large sandy estuary into which the rivers Vire and Aure, Taute and Douve discharge. The outfall channel of these rivers through the sands has been trained by rubble-stone embankments; the tide being stopped from flowing up by flood-gates, which automatically close with the rising tide and open again on the ebb. Between Grand-Camp and the Bay du Vay a shingle-bank protects some fertile land. This bank is sometimes breached in high tides, but after the storm the shingle works back and fills the breaches.
Four miles east of Grand Vay chalk cliffs commence, which rise to a height of 400 feet, and extend for 2 miles along the coast. At the Point de la Percee a shingle-bank with several fulls extends out in an east-north-easterly direction for three-quarters of a mile, being in the same direction as the set of the flood tide along the shore. Beyond the chalk cliff the coast again becomes low and sandy, the beach, which is 350 yards wide and covered with muddy sand and shingle, being bounded by sand-hills.
At St. Honorine the shore becomes precipitous, the cliffs being composed of rock and clay intersected by narrow ravines, in one of which is situated Port-en-Bessin. The shore here is steep and covered with shingle. A shingle-bank, which extends from the rocks at St. Honorine to another projection on the coast, affords protection from the sea to some marsh-land behind. The shingle at Port-en-Bessin, and also that at Villerville and other places on the coast of Normandy, has not increased in a sensible degree for a very long period, the waste by wear and tear being about equal to the supply from the cliffs.1
From Arromanches eastward for 20 miles the cliffs change to undulating hills sloping gently up from the shore. The beach extends out for some distance, in front of which is the plateau of Calvados, a rocky flat, which runs parallel with the shore for 13 miles, extending out for \\ miles, having only half a fathom on it at low water. At Courseulles the sand accumulates on the west side of the harbour, forming banks which render access to the west jetty-head sometimes difficult. There are also low sand-hills on the shore.
At Oystreham is the sandy estuary of the river Orne and a wide expanse of sand called the Bancs de Merville, which are dry at low water, extending out beyond the shore for \\ miles. The river, which formerly pursued a winding course through these sands, has been trained by stone banks. The piers and entrance here are much encumbered by the accumulation of sand after easterly gales.
From the estuary of the Orne to the river Dives the coast consists of sand-hills, which in places are half a mile wide and have a width of 800 yards.
Beyond this the coast rises, the cliffs consisting of clay and stone, fronted by a sandy beach, from 400 to 500 yards wide. There are frequent landslips along this length. From Trouville the clay cliffs continue round into the Seine; shingle being banked under them above high water, and drifting round the point past Villerville up to Honfleur.
The estuary of the Seine, which is 7 miles across from Trouville to Havre, is encumbered by a vast area of sand-beds which
1 "Etudes sur la Navigation des Rivieres a Maree," par M. Iiouniceau. Paris, 1845.