The Valleys. The valleys, as already stated, are broken and comparatively narrow; they are not conspicuous features of the topography. The Belleview valley, west of Iron mountain, is the largest within our area, while the Arcadia valley is perhaps next in size and is more picturesque and pleasing. All of the larger valleys are, without exception, underlain by the stratified rocks of Paleozoic age. These rocks consist chiefly of magnesian limestones, but near the base of some sections are sandstones which crop out at points along the margins of these areas. A glance at the map will show that these valleys are not broad plains, traversed by meandering streams bordered by alluvial lands. On the contrary, they are of the nature of troughs sloping quite rapidly from the hillsides to the very channel of the streams. Further, they are diversified by hills of varying elevation, but, as a rule, of much less altitude than the surrounding porphyry mountains. These hills are generally thickly strewn with nodules and irregularly shaped fragments and masses of chert, whence they are known as "Flint hills." This chert, a residuary product from formerly superincumbent rocks, serves as a cap to protect these valley hills from erosion and rapid removal.

HYDROGRAPHY.

More than two-thirds of the area of our sheet is drained by the tributaries of the St. Francois river to the east. The river itself is represented in the northern portion and also by a small loop along the eastern border, due east of Ironton. Westward the drainage is into Black river, in Reynolds county. The stream of most considerable size within the sheet is Stout's creek, which flows east from Ironton into the St. Francois. This is, however, only about 15 miles long from source to mouth and drains an area of not more than 70 square miles.

The declivity of all the streams is great, and water flows off quickly. Owing to the steepness of the slopes adjacent to the drainage channels, rainfall is discharged rapidly, and the streams assume a torrential character on very short notice. The water subsides, however, within a brief time. During long dry spells the creek beds are almost entirely without water.

Corrasion is vigorous along all of the streams, and especially along those flowing to the east. Thus Stout's creek falls 200 feet between Ironton and its mouth, a distance of only eight miles. The streams are, therefore, still powerful agents of land sculpture. Their channels are generally well established; though, owing to the greater

eastward declivity, a gradual transfer of divides westward is doubtless in progress.

An interesting detail of drainage here is what is known as the Shut-In, on Stout's creek just east of Ironton. Plate IV, taken from a photograph here, illustrates the scene. The stream cuts directly across a narrow ridge of porphyry, notwithstanding the fact that the ridge terminates less than a mile south of the gap, and is there surrounded by limestone strata in which the creek channel could have been cut with one-tenth of the energy expended in excavating its present course. The feature has an antecedent appearance, antecedent in that a depression probably existed in the porphyry ridges when the limestone strata nearly or entirely covered it, and when the drainage system was first outlined. A synclinal arrangement of the jointage planes, shown in the illustration, favors this idea. Once established in such a gorge, a stream does not readily desert its channel. As corrasion along the main channel diminishes, however, it is probable that the stream will be diverted by the small tributary which now enters the creek from the south just below the Shut-In and that it will eventually be carried around the point of the ridge.

Throughout the mountainous portions of our area, in the massive crystalline rocks, springs are exceedingly rare or entirely absent. In the limestone valleys, however, they are quite abundant and contribute noticeably to the water supply.

SOILS.

The soils of the Iron mountain sheet are entirely residuary. That is, they are composed of the residues left after the decay of the country rock. Over the porphyry and granite areas much of the surface of the ground is covered by fragments of these rocks, derived from the disintegration of ledges, and here little or no soil can be recognized. Where soil exists over these crystalline rocks it is generally interspersed with fragments and is thin and clayey. The forest growth, though generally thick over such areas, is small and brushy. Grass grows throughout the woods, but the best of such land is poorly adapted to farming purposes.

The productive soils of this country are in the valleys over the limestones which lie between the porphyry and granite hills. Here most of the arable land is situated. These soils are also residuary, but the products of decay from the stratified limestone, shales and sand