184 PROCEEDINGS OF THE AMERICAN ACADEMY. 



bar also is frequently converted into marsh. In the landward retreat of 

 the shoreline, this vegetable layer is discovered at or beneath sealevel, 

 covered by the beach sands, as on the New Jersey coast. 



When the offshore bar has been completely cut back, the nip has been 

 extinguished, and the sea is actively cutting into the coastal plain, leaving 

 a more or less pronounced sea cliff, maturity is reached. 



No Offshore Bar. — When the initial slope of the coastal plain is so 

 steep that the sea is able to begin the production of the submarine plat- 

 form immediately offshore, shore-grade is quickly attained, youth and 

 adolescence are of short duration, and the coast reaches a mature stage 

 of development without the production of an offshore bar. This has 

 probably been the case in eastern Italy (page 18G). 



Youth : Texas. — Tlie offsliore bars on the Texas coast are very marked features 

 in tliat elevated region (C. S., 205, 206, 207, 208, 209, 210, 211, 212). An apparent 

 earlier position of the bar is shown by the string of small islands inside the present 

 offshore bar. The sea is here building apparently from the bottom in great meas- 

 ure. The transportation alongshore as indicated by many offsets, Cavallo pass, 

 Galveston entrance, etc., is dominantly from the left, caused doubtless by the eddy 

 circulation in the gulf of Mexico. There are occasional stream deflections to the 

 left, as Cedar bayou and San Bernard river, which are caused possibly by backset 

 eddies from the main circulation. The littoral forms in this region are complicated 

 by an episode of slight drowning. A great variety of dune forms are shown 

 on this bar. 



The map of Costa Rica by Dr. Frantzius* shows a characteristic offshore bar. 

 The scale of the map is too small to show indications in which direction the bar is 

 moving, so this may be an adolescent coast. 



The eastern coast of Corsica (Fr., 2G1, 2G3, 265) shows an offshore bar, but 

 whetlier advancing or retreating, the writer does not know. 



Off the (Jgunquit- Wells Beach coast there is an offshore bar upon which the 

 writer could find no evidence as to which way it is moving. 



The offshore bars on the Atlantic slope are furtlier advanced on the whole than 

 the Texan bars. Youtliful bars prevail in Texas, and adolescent ones from North 

 Carolina to Long island. Field study of these bars is needed to bring out more 

 fully the history of the sequential forms. The following quotation shows tlie 

 meagre character of existing descriptions. 



The offshore bar opposite Beaufort harbor, N. C, "is mostly covered with a low 

 pine and mixed growth, and its average width is about half a mile ; the sand hills 

 and ridges upon it are from 20 to 35 or 40 feet high." f 



Adolescence : Southern New Jersei/. — The Geological Survey of New Jersey re- 

 ports that the sand dunes overlie a layer of black soil along the shoreline, at 

 differing heights at different localities. The lagoon along the southern coast of 

 New Jersey is largely converted into marsh, while that along the central portion of 



• * Pet. Geog. Mitt, 1869, XV. 81, Tom. V. 



t H. L. Whiting, U. S. C. G. S., 1851, Appen. 28, 483. 



