GEOLOGY. 343 



on an old tree, which was living at the time it was cut down. The trees 

 stand very thick upon the ground and grow rapidly at first, but as they 

 increase in size and crowd each other, the tops become thin and the annual 

 growth exceedingly small. The rings near the centre of a large cedar log are 

 often almost an eighth of an inch in thickness, while those near the bark are 

 not thicker than paper. Trees, four or five feet in diameter, have been found, 

 but this is uncommon, and in the second growth timber they are much 

 smaller. 



A swamp of sixty years' growth will yield from 4.000 to 7,000 split rails, 

 halves and quarters; besides the top poles or cuttings, and a considerable 

 nnmber of logs for sawing. And in the older swamps the product is propor- 

 tionally large. The value of an acre of such timber is from $400 to $1,000, 

 and some acres are thought to have yielded a larger sum still. The soil in 

 which these trees grow is a black, peaty earth, composed of vegetable matter,* 

 which when dry will burn. This earth is of various depths, from two or three 

 feet up to twenty or more, and the trees which grow on it have their roots 

 extending through it in every direction near the surface, but not penetrating 

 to the solid ground. "When the earth is open to the sun and rains, it decays 

 rapidly, but when covered with a growth of trees, and so shaded that the sun 

 does not penetrate to the ground, it increases rapidly from the annual fall of 

 leaves, and from the twigs and small trees which die and fall. This process of 

 covering and preserving timber has been going on for a long time. Trees are 

 found buried in this peaty earth at all depths, quite down to the solid ground. 

 The buried logs are quite sound, the bark on the under side of many of them 

 is still fresh in appearance, the color of the wood is preserved, and its buoy- 

 ancy retained. When these logs are raised and floated in water, it is observed 

 that the side which was down in the swamp is uppermost. The buried trees 

 are some of them found with their roots upturned, as if blown down by the 

 wind, and others are broken off as if they had stood and decayed, till too 

 weak to support their own weight. 



These logs are so abundant in some parts of the swamp, and in the salt 

 marshes bordering on them, that a large number of men are constantly occu- 

 pied in raising and splitting them into shingles. In one swamp this business 

 was commenced fifty years ago, and has been carried on every year since, 

 and though the logs are not quite so plentiful as at first, enough are still found 

 to repay the workmen. The size of the logs is from one and a half to three 

 feet, though four feet is not uncommon, and I have heard of them five or six. 

 and in one instance seven feet -in diameter. Occasionally a log is found that 

 will work for thirty feet, but generally the length is less than this. 



In searching for logs the workman uses an iron rod. which he thrusts into 

 the mud till it strikes one ; then by repeated trials, he judges of its direction, 

 size, and length. The next trial is by digging down, and if possible getting a 

 chip from it. By the smell of this the experienced shingler can tell whether 



* The amount of ash left by its burning is astonishingly small : in two trials which I 

 made, the amount of ash in the dried earth was only three and a half per cent. It was 

 almost insoluble in acids, and had not the slightest alkaline taste. It was mostly silica. 



