380 THE LESSONS OF GALVESTON 



with clear knowledge of the risks involved, and with due precautions 

 for the safety of the helpless and dependent in his own faniil}^ and 

 others. 



There is a third lesson, less simple than the first and second, but 

 far too important to be neglected : it is the lesson of coast sul)sidence. 

 already learned by Holland and Helgoland, and now forcing itself 

 on Louisiana and Texas as well as New Jersey. The student who 

 scans the shores of Atlantic and Gulf, either on the ground or on the 

 admirable maps of the Coast and Geodetic Survey and the Hydro- 

 graphic Office of our Navy, soon perceives that the relations between 

 wave-built bars and wave-cut sea-cliffs vary from coast-stretch to 

 coast-stretch. On the New .Jersey coast the bars are beaten w'ell back 

 to or beyond the line of the sea-cliffs, so that the ponds or sounds be- 

 hind the bars are relatively short and discontinuous ; along the 

 Florida coasts the keys stand farther out to sea, and are separated 

 from the mainland l)y great elongated sounds often affording navi- 

 gal)le waterways; while aljout the northern shores of the Gulf tlie 

 relations of the keys to sounds are more variable. Closer study serves 

 to interpret these variable relations : from Florida westward to Mobile 

 Bay the keys are nearly continuous and the sounds long and nar- 

 row ; thence westward to Lake iiorgne the typical keys are lost, 

 though their lines continue in a series of islands — Ship Island, Horn 

 Island, Cat Island, etc. — separated from the mainland by the broad 

 Mississippi Sound; still further westward a new series of keys, erratic 

 in form and trend, appears in the Chandeleur Lslands, and be^'ond 

 the delta there is a corresponding (and correspondingly erratic) series 

 of low keys stretching westward nearly or quite to Atchafalaya Bay. 

 Now, the mainland shore of Mississippi Sound is marked by a series 

 of small and narrow keys and sounds, evidently in process of growth, 

 but much less advanced than those east of Mol)iie Bay ; and these are 

 among the evidences that along this stretch of shore the Gulf has 

 encroached on the land to such an extent as to leave the original 

 ke3's 20 to 40 miles behind. Similarly the Chandeleur keys and the 

 corresponding series west of the delta are small and new and obvi- 

 ously connected with the delta building. But west of Atchafalaya 

 Bay the coast is characterized by the absence of keys and sounds, 

 save of the infantile sort, like those of the inland shore of Mississippi 

 Sound; so that this shore seems incongruous with the rest, until the 

 student discovers the long line of completely submerged keys — Sabine 

 Bank, Trinity Shoal, Ship Shoal, etc. — in a position precisely' corre- 



