

before the Pleisiocene or "Ice age." It could all therefore be of 

 comparatively recent origin, geologically speaking, and there Is 

 considerable reason for supposing that it is because the delta as 

 well as all of central North America was under the sea prior 

 to the Pliocene and perhaps even for a timr during the sub- 

 sequent Pleistocene. Thirty thousand feet is nearly six miles, and 

 you cannot, as I have said, push rocks down six miles in the 

 middle of a 250-milc strip without something giving way. and 

 something has. It is the surrounding surface rocks, and they are 

 being pulled down. too. so that the sea is flooding in around the 

 edges of the delta and could turn it into a great inshore island 

 Possibly because of these tremendous pressures, there are. 

 dotted about the delta and mostly along the line dividing Its 

 more modern coastal marshlands from its older deltaic swamp- 

 lands, a number of mysterious, large, circular domes. Several of 

 these, and notably Avery Island, are composed of solid rock 

 salt apparently squeezed up (in that case from a depth of more 

 than fourteen thousand feet) like paste out of a tube and then 

 spread out on top of the sediment. This Avery Island is today 

 owned by a private corporation which maintains a wonderful 

 bird sanctuary and a magnificent botanical garden there, in 

 addition to the oldest salt mine in America and a factory 

 producing the famous "Tabasco Sauce ' from oil, vinegar, salt, 

 and peppers grown on the dome. Other domes are formed of 

 pure sulphur; and from almost all of these domes oil also gushes 

 from the depths. There are oil domes both near the surface and 

 deep down. The whole strange phenomenon is caused by the 

 incalculable weight or pressure, which at depth is equivalent to 

 great heat, so that it distills or squeezes these soluble substances 

 out of the rocks in which they were entrapped; and these break 

 through to the surface when any crustal movement gives them 

 an extra pinch. The whole delta is like a vast chemical plant 

 initiated by the Mississippi. 



YOUNG MAN RIVER 



This river is still often referred to as "the biggest river in the 

 world," and such statements may even be found in schoolbooks. 

 It frankly is not so in any respect. First, it is a bit shorter than 

 the Amazon and considerably shorter than the Nile, the Nile 



Above left: The American or Common Egret. Below: Otters 



at plav 





