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Show I ANCIENT HISTORY I OF GULF OF MEXICO H Waters of Early World Onco Covered H Large Portions of the south. H Most pcoplo know in n general way H that largo portions of the United Stn- H tea have in the past been covered by H the ocean, but it is perhaps not so H generally known that the continent is H now rising in some places and sinking H Jri others. There is every reason to H beliovo thut minor movements of the H land are constantly taking place. H Not ao very long ago, in a geologic H sense, tho Hudson River flows through Hj ft deep canyon or gorgo at New York B City. Soundings show that this gorge H extends through tho harbor and far H out to sea. It is evident that tho land H surface has been lowered in this re- H gion, allowing ocean to creep in on the H allowing the ocean to crcap in on the H land, fill the old river channel, and in H ' places wholly submerge it. The aub- H . mergence of tho land was greater at H M ono timo than it is now. In oxcava- Kf Wr tionn for somo of tho Now York sky- H scrapers remains of oysters and other H salt-water animals have been found. H As a rule tho only available know- B ledgo in regard to tho former sub H mergence of an area is derived from H the marino shells and other animals H found in deposits laid down by the H sea. By the nature of tho fossils gco- H logists are ablo to tell approximately H when the ocean invnded tho land. H Thoy have found evidence of a sub- H mergence of much greater magnitude H and much older than thut which now H floods the Hudson Valley. Gothamitcs H and others need not, howovcr, feel a- H larmed at this statoment of tho ups H and downs of tho continent, for while H geologically this submorgenco is not H so very old, tho geologist thinks and H speaks in terms of thousands if not H millions of years. H Sharks' Teeth Found in Now Jersey. H Along tho Atlantic coast, from New H Jersey southward, it is not unusual to HH " find quantities of sharks' teeth and H other marino fossils in tho greensands H that are now located far inland and H are used for fertilizers. In certain H sections of the southern Mississippi H Valley whero limestone is not readily H accessible a farmer will go out und flL gather a wagon load of fossil oystor H shells to burn for lime. Tho shark- B bearing rocks of New Jorsoy and ho H oyster beds of Tennessco are of tho W rockB are said to bo of Cretaceous B,f When Gulf of Mexico Reached Cairo. v In the courso of its investigations B of the geology of tho country, tho MB. I United States Geological Survey has HHKj been making a study of tho Crctaco- H ous deposits of the Eastern States Pj and has found that tho ocean of that HHHJ time covered much of what is now the fl Atlantic Costal Plain, while tho Gulf H' i of Mexico spreads widely over the cen- B ' tral Southern States, probably reach- ' ing as far north as Cairo, 111. The BSM. Ohio was then a 'longer and older river than the Mississippi. Somo of the sediments of this age, now hard- BSB ened into rocks, were deposited in a shallow sea, some about the mouths of BVM rivers, and some perhaps in the flood plains of the rivers themselves. All MB these different types of sediments, as BBBB found in the eastern Gulf retrion. aro BBMfl described in the United States Geo- HMMM logical Survey's Professional Paper HMMH 81, by L. W. Stephenson. In another HMMM portion of the paper is a discussion of MM certain oysterlike shells found in these MMMM Cretaceous rocks, all tho known spe- MMMM t cies being described and figured. H The P-per is of interest to those Hl Hving in the eastern Gulf region not MM only illustrating the geology of MM the area but; as indicating the distri- MMMMi bution of certain types of rocks. As MMMj tho soil is made in large part by the MMH slow decay of the underlying rock, MMMM It naturally follows that certain sorts H of rock furnish better soil and subsoil MMMM! than others. By means of tho map MMMM included in tho report tho extent of MMMM different geologic formations enn bo MMMM MMMM Professional Paper 81 may bo ob- MMMM tained without cost by applying to MMMM Pircctor of the United States Geolog- IXUflj ,kl Survey, Washington, D. C. |