90 THE EOCEXE DEPOSITS OF MAEYLAXD 



bearing rivers, while at the same time, for the most part, sufficiently 

 removed from the coast-line to he imaffected by shore conditions. It is 

 further evident that these deposits, Avhich are so largely glauconitic, were 

 very slowly accumulated, as has been sho^^vTi in the case of the formation 

 of greensand upon the beds of existing seas. 



When we compare these conditions of accumulation on the Middle 

 Atlantic Slope Avith the conditions that prevailed in the Gulf region 

 during Eocene time marked differences appear. In the latter area 

 numerous rivers, draining the interior of the continent, discharged large 

 quantities of material throughout much of the Eocene, making the 

 deposits highly diversified. Instead of the greensands and greenish and 

 black clays of the Middle Atlantic Slope, which no longer to any great 

 extent characterize the strata, are found coarser beds of sand and clay, 

 often partly calcareous, which give every indication of more rapid 

 accumulation. To compare, therefore, the 200 to 300 feet of green- 

 sands and clays of the Middle Atlantic Slope with one or two subdi- 

 visions of hardly equal thickness in the Gulf region would scarcely be 

 attempted, even upon geological grounds. The strata of the Middle 

 Atlantic Slope must be represented in the Gulf by deposits many times 

 their thickness. 



The State Geological Survey of Alabama has estimated the total 

 thickness of the Eocene beneath the Jacksonian at 1500 feet, 600 feet 

 of this belonging to the Chickasawan and 450 feet to the Claibornian. 

 The Lower Chickasawan is given a thickness of about 350 feet and the 

 Upper Chickasawan a thickness of about 250 feet, the Bells Landing 

 division of the former having a thickness of less than 150 feet. The 

 paleontological evidence previously cited, combined with the geological 

 data here presented, show the far greater thickness of the geologically 

 contemporaneous dejDosits in the Gulf as compared with those of the 

 Middle x\tlantic States. 



Furthermore the general relations of the strata, occurring as they do 

 between the Cretaceous and iSTeocene along both the Atlantic and the 

 Gulf coasts, give some indication of the continental movements t(j which 

 each province was subjected. Although the movements may not have 

 been absolutely contemporaneous, they nevertheless afford satisfactory 



