The Elements of economic geology

Bibliographic data

Monograph

Identifikator:: 1773832379

URN:: urn:nbn:de:zbw-retromon-172798

Document type:: Monograph

Author:: Gregory, John W. http://d-nb.info/gnd/11683014X

Title:: The Elements of economic geology

Place of publication:: London

Publisher:: Methuen

Year of publication:: 1928

Scope:: XIV, 312 S.; graph. Darst.

Digitisation:: 2021

Collection:: Economics Books

Usage license:: Get license information via the feedback formular.

: tc {1 Pig ER 5 £ g £9 T nN {0 nN & m wh > on ND fey COASTAL WORKS 239 out 50 feet high. In the North Atlantic the maxi- out 40 feet. Vaughan Cornish (Waves of the Sea, J, during a strong gale in December, 1900, measured es 20 feet high, and some of 43 feet. The height pon the * fetch,” i.e. the width of open water to ; if the fetch is more than 39 miles the height es (H) in feet is one and a half times the square e fetch (D), i.e. H = 1:54/D; if the fetch is less iles H = 1'5 (2:5 — 4v/D). The heights of waves, to the formulas, are as follows :— >. 5, Vave Height. Fetch, Wave Height. Fetch. ‘Wave Height. | 5 3 ft. 5 ft. 6 in. | 7 ft. 1 in. 30 miles = 8 ft. 4 in. 40 ,, =gft. 5 in. 50 ,, =10ft. 6 in. 100 miles = 15 ft. 200 ,, =2Ift.5in, 300 ,, = 26ft. ~ - — jo wo on > res in Lake Geneva are 8 feet high where they have 40 miles, those on Lake Superior 20-25 feet high ch of over 300 miles. ith of disturbance of a wave is equal to its length ; num length of ordinary waves in the Atlantic is nd they disturb fine sediment to the depth of about or 100 fathoms. The action diminishes rapidly a. The displacement of water particles at a depth he length of the wave is only xls and at double Lis only yggsyy of that of the surface. At special ves and currents move material far below the imit of wave action. Lobster pots in the English re sometimes filled with coarse shingle at the depth i feet. Seaweeds which live not less than 200 feet vashed ashore with stones attached to their roots, have been torn from the sea-floor by waves. The !legraph cables is cut by drifting sand at the depth ;, and silt is moved at greater depths. nsport of beach material depends on the angle at ‘es strike the shore. A wave which rushes obliquely ach returns by the shorter steeper course at right the shore ; it carries material along a zigzag course. rash may be concentrated and strike a more power- han the oncoming wave; thus at Dunbar a wave 1 z =} NY oO a 0 ~l

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