THE OYSTER-INDUSTRY. 17 



E. C. Cliapmaii, of Newcastle, Maine, who lias paid mncli intelligent attention to the matter, has constructed a 

 theory in this wise: He points to the fact that the fresh- water pond above the island and rocky l^xlls at Damariscotta 

 mills is about (iO feet higher than the level of Salt bay. The tide never goes beyond these rapids. He believes 

 that at one time the pond coutained a far greater volume of water than now, and that it had either no outlet at 

 all into Salt bay, or else a very small oue ; but that finally the weight of the water broke through the barrier of 

 rock and gravel at the falls, and made for itself this new channel oceanward. This breakage would of course 

 burden the new outrushing current with an enormous amount of loosened soil and broken rock, which would be 

 swept onward until it settled in thick sediment all over the bottom of Salt bay, and ibr a long time after the water 

 would be murky with clouds of mud. Such a catastrophe would undoubtedly kill the most, if not all, of the 

 molluscan life in such an inclosed body of sea-water as Salt bay is ; and the oysters would survive it least of all. 

 But I am not convinced that there is e^idence that any such a sudden, grand disaster ever occurred at that spot, 

 or, if it ever did, I am of the o]uniou that it was antecedent to the beginning of the shell-heaps. We are all more 

 fond of conjuring up some grand cataclysm to account for mysteries in nature, than to accept an explanation 

 commended by its simplicity. 



Pollution of the wateb by mills and factoeies.— One of the first acts of the new settlers was the 

 erection of saw-mills at the falls, where they found a splendid water-power. These mills began at once to pour 

 great quantities of saw-dust into the stream, which was carried out into Salt bay and the river below, where it was 

 bandied back and forth in the tireless tides until it sank. Sawdust very soon becomes water-logged and goes down. 

 At the same time woodmen were clearing the forests and draining the swamps, and farmers were breaking the turf. 

 Each of these operations tends to increase the running off of the rain and the carrying away of a far greater amount 

 of silt than under natural conditions. The oysters thus found their clear, salt home freshened by an unusual influx 

 of rain-water, the currents always roily, and themselves gradually being smotheretf in the sediment of sawdust and 

 earth deposited everywhere, except, perhaps, in the deepest and swiftest parts of the channel. Thus an end was 

 made of what, with care, might no doubt have been nurtured into a most flourishing oyster-colony. 



At the northeastern extremity of Salt bay a little stream, known as Oyster creek, comes in from toward the 

 village of Nobleboro. The mouth of this creek is out of the way of the currents from the mills, and, in general, it 

 is the part of the bay least likely to suffer harm from sediment. The men who fish for eels through the ice in winter 

 say that underneath the foot or so of thick sawdust and mud that now covers the bottom, and has perceptibly 

 lessened the general depth of the water within a hundred years, there is everywhere a layer of oyster-shells. 

 Here in the creek, however, these are not covered up, but may be seen lying, large and white, on the bottom, as the 

 bridge is crossed. IMoreover, men now living assert, that sixty or seventy years ago a few of the bivalves were still 

 to be had there, and that during the previous half century there were a great many in the bay. They believe that 

 later than that scattering individuals might have been found, and some men go so far as to say that in the " quick- 

 water " at the base of the falls a few oysters may even now be obtained. There are some supporting facts, and I 

 do not think it unlikely. 



The covering of the formerly gravelly or shelly bottom of the bay would not only smother existing mollusks, 

 but, in the case of our subject, would prove fatal in another way. The spawn of the oyster requires some clean, 

 firm support to which to attach itself. The soft, wet matting of sediment would not do at all, and all the ova would 

 drift out to sea or become the food for fishes, and in either case produce nothing. 



No longer than forty years ago, however, I am told, a dead spruce tree was dragged to the surface opposite the 

 shell-heaps, whence it had fiillen, top foremost, into the stream. The branches were clogged full of sawdust ; but 

 clinging to the twigs were innumerable young oysters that had not had a chance to grow to any great size before 

 they were choked by the drifting sediment. Whence came the spawn for this growth, if there were then no living 

 oysters in Salt bay or vicinity"? It is possible some might be got, by careful search, in the Oyster creek corner yet. 

 As lor the long, thick shells dredged up in the lower Penobscot river and in Portland harbor, indicating so 

 extensive a habitancy there of these mollusks in ancient times, possibly the death of many of them dates back to 

 Postpliocene days. Opposed to this thought, nevertheless, is the fact that shell-heaps upon the islands in Casco 

 bay show that a few oysters, at any rate, still existed when Indians dwelt there. No one has ventured on an 

 exi)lanation of their extinction, that I am aware of, except Mr. C. B. Fuller, curator of the Portland Society of 

 Natural History, who suggests that, by the breaking away of the barrier represented by the present chain of 

 islands in the bay, the water of the outer sea was let fully into what had previously been a sheltered basin. This 

 water was so very much salter, as well as colder, than that to which the oysters had been accustomed, that they 

 were unable to survive the change. 



Climatic changes. — Professor A. E. Verrill, however, evidently considers a change in climate the cause of the 

 loss to the world's economy of these storehouses of food. In his Invertebrates of Vineyard Sound, this writer remarks 

 that the occurence of large quantities of oyster-shells beneath the harbor-mud at Portland, associated with T'e«M« 

 mercenaria, Pecten irradians, Turhonilla interriipta, and other southern species, now extinct in that locality, and the 

 occurence of the first two species in the ancient Indian shell-heaps on some of the islands in Casco bay, though not 

 now found living among the islands, indicates that the temperature of those waters was higher at a former period 



