2. Reticulated kame-plains.-Often a single ridge divides into two branches which soon come together again and thus enclose a sink or funnel, which may, if it be low enough, contain a lakelet without visible outlet or inlet. Or, a kame may expand into a series of ridges connected by cross ridges and enclosing numerous funnels or lakelets. These plains are often many miles in length and from one to five miles in breadth.

3. Solid or continuous kame-plains. These are broad and massive plains, or ridges usually quite level on the top and showing few or no funnels or signs of separate ridges. They are in fact an enlargement of the kame and are often higher or lower than the narrow ridge which may be found both north and south of them. Several kame systems in the Androscoggin-Kennebec region break up into a series consisting of these broad, solid plains or ridges, separated by gaps of a mile or somewhat more. Some of these solid plains are 140 or more feet in height. They may be one mile in breadth and several miles in length. If long, they are usually not very broad.

THE INTERNAL STRUCTURE OF KAMES.

Internally kames are of two classes.

1. The stratified kame, which is the more common kind.

2. The pell-mell kame, composed of the finest and coarsest materials indiscriminately mixed. Occasionally a kame contains what appears to be upper till, as if a mass of till had slid down into the channel of the stream and defied classification by the current. In general the rounding of kame material is very conspicuous. In some cases pebbles from two to four feet in diameter have been made almost spherical. The rounding of kame pebbles or cobble stones is not like that of our ordinary streams, but resembles that of the pebbles found in pot-holes or on the sea beach. Some of the stones of the ground moraine are rounded in a very similar manner. In order to account for this extreme rounding of kame pebbles we must suppose great violence and vertical movement of the waters of the kame river, or that the movements of the glacier assisted in the rounding process, or perhaps that both of these causes were combined. A kame is sometimes found to be stratified in some parts of its course and pellmell in others.

ACTION OF THE SEA UPON THE KAMES.

During the Champlain period the sea probably stood in the central parts of Maine, at a height of 300 or 350 feet above the present sea level, and many kames were submerged during that period. The sides of the kame that has not been under the sea usually slope at the angle of stability of loose materials in air, while marine waves and currents often reduced the kames to the form of low rounded bars, whose sides slope at the angle of stability of such materials in water. The fossiliferous Champlain clays have hundreds of times been seen overlying the kames and I have taken mya, balanus, and other marine genera from the undisturbed clay found in a depression in a kame. The difference in the physiognomy and structure of the kame which has been under the sea and that which has not, is so great as to show conclusively that the kames proper cannot have been a marine deposit.

DISTRIBUTION OF THE KAMES.

A line joining the northern extremities of the longer kames is nearly a straight line; it trends nearly northeast and is roughly parallel with the coast. North and west of this line there are occasional short ridges of kame origin, but no long systems have yet beer discovered. The writer's theory as to the cause of this is, that it is chiefly a matter of slope. On a long slope northward or northeastward, the action of the melting waters of the great glacier must have been very different from what it was on a southern slope of seven feet per mile. For the full development of kames a medium slope is necessary, also that the melting proceed simultaneously over a considerable area.

TOPOGRAPHICAL RELATIONS OF THE KAMES.

We have already referred to the numerous ranges of hills in Maine, which lay athwart the course of the glacier. All of the longer kame systems cross one or more of these high transverse ranges, but never except by low passes, that is, passes not more than about 200 feet above the country lying to the northward. Hills lower than this they cross freely, and, indeed, are found in all relations to them, now turning aside as if to avoid a hill not more than 100 feet high, and soon crossing such a hill when it might avoid it by as short a course or even shorter. In some cases

where a kame breaks up into a series of disconnected ridges or solid plains, like that which passes through Portland, the gravels are found on the higher land, but this rule is not followed by some other similar discontinuous systems (XVII, XX). While following a valley the kames may sometimes be found along the axis of the valley, but more commonly approaching the bordering hills, first on one side and then perhaps on the other. After entering valleys they are not known to leave them when the bordering hills are more than about 200 feet high, and they do not ordinarily leave a broad south-southeasterly valley even when bordered by hills much lower than this. Valleys of other trends they very often enter and leave them again or cross them. This is well illustrated by the courses of systems VIII, IX, XI, and XXIV. For instance, IX runs lengthwise of the valleys of seven streams, and crosses five, besides entering the Penobscot valley twice, following it for a few miles, and then again leaving it for higher ground. The reason the kames run lengthwise of so many valleys is that they follow up a stream to its source, cross a low col and then follow down the valley of a stream flowing in the opposite direction. In general the courses of the kames are straighter than those of the longer rivers, for the latter are deflected by the east and west ranges of hills, while the kame rivers might take a direct course through some low pass, and thus often reënter the valley of the same river which they had just left. Where there are several passes the kame does not always take the lowest or most direct, in which case it is sometimes found that by so doing the kame, some miles toward the south, secures a more favorable pass than if it had taken the other route. This is the anticipatory choice of water rather than the blindness of the moraine. This relationship between the kames and the low passes is of inestimable service to the explorer when in a hilly or mountainous region. The first part of his problem is to determine where are the low passes. He may thus be able to predict the courses of the kames for many miles ahead, and will know where it will be profitable to explore. 'The inference of the writer is that the kames were deposited late in the ice period, when the glacier was so far melted that the higher hills rose above the ice surface, and hence the only escape for the waters southward was by the low passes.

PRESERVATION OF FOSSIL INSECTS AND PLANTS ON MAZON CREEK. By J. W. PIKE, of Vineland, N. J.

THESE fossils are the admiration of collectors, and have a special interest for students of natural history and geology. As delicate copies of the structure of ancient plants, insects, crustaceans, etc., they are unsurpassed. There are inscribed on these beautiful "figured stones" not only the most accurate geological notices, but the finest hair lines from the leaves of ferns, the wings of insects, the limbs of crustaceans, the scales of fishes and reptiles.

Mazon Creek is a branch of the Illinois river, which it joins at Morris the county seat of Grundy county. From five to seven miles above its mouth, the waters of the Mazon have carved their channel through prairie soil, drift, and sandstone, into the blue shale bed in which the fossils are found. Below the shale is a bed of coal which has been opened, in places, by shafts sunk below the level of the stream.

Suppose we are on the ground, desirous of interpreting the geological and biological history recorded in these deposits. We must resort to the method of comparison, upon which all scientific interpretation rests. Beginning with the bed of fossil fuel upon which the shale rests, we compare it with other deposits of carbon, with lignite, peat, and the accumulations now forming in great swamps. By the method of comparison the facts of our Mazon Creek deposit are brought into relation with similar facts, as universal as the world, and scientific insight is acquired. In the underclay are the Stigmaria with their delicate rootlets. We compare them with cedar, cypress and other roots in the swamp mud under modern peat beds, and conclude that the underclay is the muddy soil of an ancient swamp. By a similar method it becomes evident that the coal is a mass of vegetable matter which slowly accumulated in the stagnant waters of the swamp, and was subsequently pressed into a solid bed. Comparison restores the landscape: we see the half submerged shores and islands, the jungle of marsh plants, the debris of trunks, branches, vines and leaves, settling under the dark stagnant water.

The first layers of shale, that lie above the coal, mark a gradual increase of water over the surface. Compare its flattened tree stems with the perishing forests now being entombed in mud,

where the Atlantic coast is sinking. As the water deepens, the fringing swamp advances upon higher ground, and layers of clay are spread over the deposits of peat and logs. The Mazon shale must have resulted from similar conditions. Compare it with the blue clay now accumulating, where the rising water has flooded valleys and swamps transforming them into shallow bays and lakes. The clay brought down from the land by rivers and coast waves may be yellow or red. It subsides upon the bottom with decomposing organic matters which reduce peroxide of iron to protoxide, and the clay deposit becomes blue. This shale, then, is the product and record of a subsidence that buried the older swamp, with its deposit of carbon, under the waters of a lake. It formed as a soft ooze over the buried peat, and in it the remains of crustaceans, fishes and reptiles that inhabited the water, were entombed.

Compare the leaves in these concretions, or lumps of hardened shale, with those being buried in the sediment of modern lakes. As they float from the marshy shores and sluggish streams and become water-soaked, they sink flat upon the fine mud below. After successive layers have been sifted on them by the water, they are found conformable with the strata in which they are buried. So it is with the leaves in these nodules. Among a thousand specimens it is difficult to find one twisted out of conformity, even at the point, like this one. On the other hand, the extreme softness of the shale at that time is shown by the size of these base leaflets, which were thrust diagonally into it by the mere weight of the blade in water. Such was the geological page upon which these biological records were inscribed.

Comparison develops the inscription into a restored landscape. An impenetrable tangle of ferns, rushes and other lowland plants skirts the rivers and shores, stretching away in broad savannas farther than the eye can penetrate. The drooping foliage trails in the black waters of swamp-lined rivers. Creeping things of strangely generalized form, covered with scales, bristling with spines, are swarming in the murky air, on the moist ground, upon the dense foliage and in the stagnant water. There are roaches, locusts, may-flies and termites; spiders, scorpions, centipedes and caterpillars; creatures something like these, and like crabs, shrimps and craw-fishes. They float along with the fallen leaves, sink down upon the soft bottom and are buried in the growing shale bed,