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Page:Popular Science Monthly Volume 70.djvu/562

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sedimentary deposits consisting of clay, sand, sand and gravel, coarse gravel and finally large pebbles.

Over the outer portion of the sandy bottom, also for great distances beyond, as well as up and down the river wherever extensive silting has developed the formation of muddy bottoms, there is an abundant growth of eel grass (Zostera marina) which, together with other d├ębris of a similar nature, is continually washed upon the beach, broken up by the combined action of the waves and sand and gradually buried in the latter, so that each year the deposit of organic matter is increased by definite though rather slight increments.

From these data it will be observed that some special significance attaches to the fact that the fire, on two separate occasions, was strictly confined to the beach, and that it did not in any way extend over the limiting areas of rock.

On the evening of Friday, September 1, 1905, the guests in the hotel, the piazza of which may be seen on the extreme right of the photograph, were startled by the appearance of flames rising from the beach and also from the surface of the water. The tide was about one hour lower than shown in the photograph, so that a very considerable portion of the sand was uncovered. The conflagration occurred between seven and eight o'clock in the evening and lasted for upwards of forty-five minutes. It was accompanied by a loud and continuous crackling noise, which could be distinctly heard one hundred yards distant, due to the rapidly recurring explosion of bubbles of gas as they came to the surface of the sand or water. At the, same time there was a very strong liberation of sulphurous acid gas, which penetrated the hotel, drove the proprietor and his staff from the office and filled the other rooms to such an extent as to cause great inconvenience to the guests. So great a heat was developed that the sand could not be held in the hands, while sand placed in a tumbler with water and then stirred, liberated bubbles of gas which ignited upon coming in contact with the air. On this occasion the fire developed over that portion of the sand which had been exposed by the falling tide, and it also extended out over the water for a distance of thirty or forty feet.

On the evening of Wednesday, October 4, 1905, as reported by a reliable observer, the phenomenon was repeated with identical features, except that instead of occupying the entire area between the rock formation on each side, it was restricted to the area where the two boats are lying. It therefore occupied probably less than one fourth the area of the first conflagration.

It is difficult to estimate the height of the flames on these two occasions, since the conditions under which the fire occurred would tend to give an exaggerated value. It is probable that in general the flames were not more than three or four inches in height, and this would be a reasonable estimate when arising from small bubbles of gas. But, as stated in the original account, the flames attained a maximum