course, and so the uppermost parts of the marshes are formed 

 over a very long time and the lower parts of the marshes in a 

 shorter time. It hasn't yet been worked out in much detail. 



Oppenheimer: Do you think that in the course of the water passing over a 



channel that the velocity would pick the sand grains up, move 

 them along, and would have scoured that fine-grained mud away 

 before ? 



van Straaten: Yes, it is quite possible at many places, especially at meanders. 

 The back stretch of meanders has a tendency to receive the cur- 

 rent all the time, and at slack tides, a layer of mud is left. The 

 next ebb current or flood current that passes there takes away 

 the greater part of that mud layer, and the ebb current itself 

 brings new sand which covers what is left of the mud. 



Discussion at end of van Straaten's paper 



Zeigler: I have a "Little Goliath" proposal to make. This came from a 



devastating attack last night upon some of my earlier ideas 

 about the formation of barrier islands by Professor Steers. I 

 wish to implicate Dr. Bradley and Dr. Teal so that they cannot 

 wiggle out of this. We were discussing the origin of these barrier 

 islands such as you have along the coast of Texas and the coast 

 of Virginia. The point was raised that perhaps to begin with an 

 offshore barrier is cheating, that you must explain it before 

 you begin with it, and we were in no mood to accept the hypotheses 

 of Professors Johnson and Davis, although they may be correct. 

 So we came up with a new one and I have christened this the 

 "Little Goliath". We start with an original profile and this is 

 at a point in time when sea level was much lower (Fig. 6a). 

 A beach gets shoved forward as the sea rises, so maybe about 

 4000 years ago at the time of the Climatic Optimum this roll 

 of sand would be up here (Fig. 6c). Now, following the Optimum, 

 1 would like to see the sea dropped just a little bit leaving this 

 nice little ridge of sand behind with the sea backed down for a 

 while. Meantime you get vegetation here and you get wind action 

 and you get high dunes on it, and you have built part of a barrier 

 island. In this case, you do have a low spot behind it, and if 

 rivers drained into there (i.e., behind the barrier), they would 

 aid in making this depression more pronounced, both by scour- 

 ing and by filling in a little bit of marsh. Now we will let the 

 sea begin to rise again. As it reaches its old shore and floods 

 in behind it, you begin to get marshes behind an offshore barrier. 

 If this is so, it might explain why you have so many world-wide 

 occurrences of these great long barrier islands which extend for 

 hundreds of miles. At least, beginning on the Gulf coast and 

 going right around Mexico and on our own Atlantic coast froin 



18 



