CHAPTER VI.

THE WORK OF THE OCEAN.

Volume and composition, 324. Topography of bed, 326. Distribution of marine life, 328.

+Processes in Operation in the Sea+ 329 Diastrophism, 329. Vulcanism, 332. Gradation, 333.

+Movements of the Sea-water+ 334 Differences in density and their results, 335. Differences in level and their results. 335. Movements generated by winds, 336. Movements generated by attraction, 322. Aperiodic movements, 338. Summary, 339.

+Waves+ 339 Wave-motion, 339.

+Work of the Waves+ 342 _Erosion_ 342 By waves and undertow, 342. _Topographic Features Developed by Wave Erosion_ 349 The sea-cliff, 349. Chimney rocks, etc., 350. Sea caves, 350. The wave-cut terrace, 351. Wave erosion and horizontal configuration, 353. _Transportation by Waves_ 354 _Deposition by Waves, Undertow, and Shore Currents_ 355 The beach, 355. The barrier, 356. The spit, the bar, and the loop, 357. Wave-built terraces, 363. _Effect of Shore Deposition on Coastal Configuration_ 363

+Summary of Coastal Irregularities+ 364

+The Work of Ocean-currents+ 366

+Deposits of the Ocean-bed+ 368 _Shallow-water Deposits_ 369 Littoral deposits, 369. Non-littoral, mechanical deposits in shallow water, 369. Characteristics of shallow-water deposits, 373. Topography of shallow-water deposits, 374. Chemical and organic deposits, 375. Limestone, 378. _Deep-sea Deposits_ 378 Contrasted with shallow-water deposits, 378. Sources, 380. Mechanical inorganic deposits, 380. Organic constituents of pelagic deposits, 382. Chemical deposits, 383.

+Lakes+ 386

Changes taking place in lakes, 387. Lacustrine deposits, 388. Extinct lakes, 388. Lake ice, 389. Saline lakes, 391. Indirect effects of lakes, 392. Composition of lake waters, 392.