and increases in depth until it may be some feet in thickness; next the shore it rests upon the bottom, but in deeper water it floats with its surface a foot or so above the water. From the lower margin of this raft of moss the dead parts of the plants fall upon the bottom and by their decay from the familiar black mud or soft peat which often gathers to the depth of twenty or thirty feet. Given time—and in a geological sense no long period is required-and a lake a mile or two in diameter will be closed over and solidly filled with the muck deposit. Only when the lake is of such area that heavy waves may form on it, which serve to break up the advancing mat of vegetation, is it preserved from this agent of obliteration. The result is that by far the greater number of the glacial lakes formed in New England when the ice of the last glacial period disappeared have been converted into peat bogs; probably more than nine-tenths of them have been thus closed. Further to the northward, where the ice went off in more recent times, than near its border, the process of occluding the glacial lakes is naturally less advanced than in New England. In these we more often find "quaking bogs," i.e., instances in which the sheet has closed over the lake, but where the deposit formed on the bottom has not been built up to where it supports the mat so that the peat-making process is complete.

Upland or climbing bogs. The foregoing sketch of the history of peat morasses formed in lakes needs to be supplemented by an account of another method of their development, which in many parts of the world where the air is moist and cool gives rise to even more extensive deposits -those known as upland or climbing bogs. In this group the sphagnum begins its growth on the margin of any pool and extends its sheet away from the water so that it mounts slopes of considerable steepness, sometimes ascending to heights of a hundred feet or more in an advance of a mile. As it grows in thickness, the lower part of the mat dies and so forms an ever-increasing mass of soft peat on which the

living tangle rests, holding, as in a sponge, the water needed for its growth. So effectively does it do this that in times of heavy rain the bog swells up and occasionally it bursts, discharging a tide of black mud which flows like a lava stream, in many instances carrying widespread destruction to farms and villages in the valleys through which it flows.

In effect the fields covered by climbing bogs are limited to regions north and south of the parallels of 40° in either hemisphere, for there alone do we find the relatively low temperature and the high measure of humidity needed for their development. They originally mantled a considerable part of the land now tilled in the northern part of Great Britain, nearly all of the lower ground in Ireland, and much of the most fertile portion of Germany and Scandinavia, about the shores of the North Sea and the Baltic. They still exist in vast development in Northern Russia and Siberia, in Patagonia, and in Canada. South of Canada, they are so scantily developed as to have no interest from our point of view. In Africa and Australia they find no place because of the high temperature or the dryness of the air, both of which conditions prevent the growth of the bog-making mosses.

Area reclaimable from bogs. It is not easy to estimate the amount of tillable soil which can be won from the fields now possessed by moss bogs; it may be taken as probable that the aggregate area exceeds 300,000 square miles; it being, perhaps, the largest part of the earth's surface which can be won from the covering of water. Should it prove possible to develop tillage in any considerable part of the tundra of Siberia the total may much exceed that amount; it may on those conditions rise to near half a million square miles.

As for the quality of the soil obtained from these peatcovered fields, experience shows that, though variable, it is good for a wide range of uses. The fields whence the climbing bogs have been stripped are of great and enduring fertility. The level bogs of the deposits which have filled lakes have a different character; they cannot so readily be brought to

tillage. In fact, it is commonly necessary to strip the mat of living sphagnum off and then to cover the surface with sand or mix the upper part with ordinary earth. Thus treated the ground becomes well suited to a great range of important plants, especially those reared in market gardens. The interesting industry of cranberry growing is one of those forms of tillage in which the peat soil is turned to account. In fact this species of plant will not commercially develop in any other conditions save those of drained swamps.

Area reclaimable from lakes. One of the largest bodies of unwon yet winnable lands is that now covered by the waters of lakes. Their drainable areas are very numerous, especially so in glaciated districts in the part of North America recently occupied by the ice-fields. Their basins are to be reckoned by the tens of thousands, and their aggregate area is probably not less than fifteen per cent. of the field in which they lie. The greater number of them, though probably not half of the total surface, are to be, in whole or in part, drained and brought under tillage as soon as population begins to press upon means of subsistence. The ground thus made available for tillage is likely in North America to amount to not less than twenty thousand square miles.

The quality of the soil to be won by the drainage of lakes will in most instances be excellent. These areas of water, though in practically all instances of geologically recent origin, have been long enough in existence to have enriched their bottoms with deposits of lime phosphate and other materials favorable to the growth of plants. The soils drained from these accumulations will be prevailingly clayey and rather heavy, but very little enduring to tillage and of far more than average fertility. They may be reckoned on to afford fields as well suited to agriculture as the heavy land of Northern Ohio, Indiana, and Illinois, where much of the surface took on its character below the former extension of the neighboring Great Lakes.

Lakes other than glacial. Although the greater number

of drainable lakes and the largest aggregate area of them lie in the glaciated districts, there are many such in parts of the world where the ice-sheets have not shaped the surface. Other fresh-water basins are among the results of mountain-building actions which have lowered considerable areas, forming such lakes as the Dead Sea of Judea, or the extensive lakes of the upper Nile. Many of these basins are so deep, their bottoms often lying below the sea-level, that complete drainage is impossible in many, if not most instances. However, the conditions often make it possible to lower the surface of the water to such an extent that large fields of good land may be won.

As a whole, the lake beds may be reckoned on as likely to afford, in the ages when the earth is crowded with men, a resource in the way of tillable lands in area comparable to that which may be had from the deserts, the morasses, and the shallow fringes of the sea.

CONSERVATION OF NATIONAL RESOURCES

The

[THE President of the United States created June 8, 1908, a National Conservation Commission of five members, with Gifford Pinchot as chairman, to inquire into the condition of the national resources. final report of the Commission, made December 7, 1908, was a brief summary in about fourteen pages of the large body of information collected. The report was submitted to a Joint Conservation Conference meeting in Washington, December 10, 1908, and made up of governors of States, State Conservation Commissions, and representatives of numerous scientific and civic organizations. The Conference having heard the report and "having fully deliberated thereon," indorsed it "as a wise, just, and patriotic statement of the resources of the nation, of the thoughtless and profligate manner in which some of these resources have been and are being wasted, and of the urgent need for their conservation in the interests of this and future generations, to the end that the prosperity and perpetuity of the nation may be assured."

The report opens with a general statement of the causes arousing public interest in the subject. Omitting this and a number of the recommendations of legislation contained in the report, the following extract reproduces almost entire the remarkably compact statement of facts regarding our national resources at the time of the report. The complete report accompanied by Proceedings of the Joint Conservation Conference, and by numerous scientific papers (in all nearly 1800 pages) was published as Senate Document 676, for the 60th Congress, 2d session, Vols. 10, 11, 12.]

Minerals. The mineral production of the United States for 1907 exceeded $2,000,000,000, and contributed 65 per cent. of the total freight traffic of the country. The waste in the extraction and treatment of mineral products during the same year was equivalent to more than $300,000,000.

The production for 1907 included 395,000,000 tons of bituminous and 85,000,000 tons of anthracite coal, 166,000,000 barrels of petroleum, 52,000,000 tons of iron ore, 2,500,000