The study of the peak, and its long gently-inclined lava ridges, was replete with important facts, and observations bearing upon the nature and laws that governed the volcanic outflows; but among the most interesting discoveries incident to the trip was the finding of existing glaciers upon the southern slope of the mountain.

The summit of Mount Hood exposes upon the east, north, and northwest sides a bold, precipitous, jagged mass of rock, which forms the outer wall of the old crater, encircling it for three-fifths of the circumference. The remaining portion of the wall is wanting, the other two-fifths presenting a comparatively even slope down to the timber-covered ridges below.

The crater is nearly one-half a mile wide from east to west. The wall upon the inner side rises above the snow and ice filling the basin some 450 feet, while upon the outer side it falls off abruptly for 2,000 feet. This rim of the crater is very narrow; in many places the crest is not more than two feet wide.

Three distinct glaciers have their origin in this basin, each the source of a stream of considerable size; the glaciers of the White, the Sandy, and the Little Sandy rivers.

The White river glacier heads on the eastern side of the crater, and extends in a southeasterly direction. It is nearly a quarter of a mile wide at the head, and about two miles long, extending 500 feet below the line of timber-growth upon the sides of the mountain.

Near the top of the crater a broad transverse crevasse cuts entirely across the glacier. Freshly fallen snow overhangs in projecting banks, the perpendicular walls of ice, making it exceedingly dangerous to approach. At one point only, the fissure may be crossed by an ice bridge. Further down the slope of the glacier transverse crevasses are of frequent occurrence, running nearly parallel with each other; most of them are, however, quite narrow. One broad chasm presented clean, sharply cut vertical sides, for nearly 200 feet in depth, of clear deep blue ice. Marginal crevasses, ice caves and caverns occur; many of the latter are very beautiful and afford fine opportunities for the study of the laminated and veined structure of glacial ice.

Very many of the phenomena attendant upon glaciers elsewhere may be observed here. The terminal and lateral moraines are well marked and extensive. Medial moraines, however, do not appear, because the glacier has no tributaries. Glacial grooving, glacial débris and boulders are quite characteristic.

The glacier of Sandy river is separated from that of the White river, by a high bare ridge, standing boldly up above the ice and dividing the crater into two parts. The glacier

descends to the southwest. It is fed by the snow and ice of a somewhat larger area of country, and is considerably broader than the glacier of White river. In length they are about equal.

An immense amount of glacial débris must be annually carried down the stream, whose waters are heavily charged with fine light gray trachytic sand, brought down from above by this moving mass of ice. The character of the rock, a brittle, porous trachyte, is such, that under the wearing action of the glacier it would be easily eroded and ground to fine powder. The very extensive accumulations of sand-banks, which are constantly forming at the mouth of the stream, where it empties into the Columbia river, bear ample evidence of the fact.

The Little Sandy river, a tributary of the main stream, with which it unites, a few miles below the base of the mountain, has its source in the third glacier, which is formed on the western flank of the peak, separated from the Sandy by a high wall, a somewhat broken irregular ridge of trachyte, which extends along the southwest slope of the mountain.

The upper portion or the névé of the glacier is inclined at quite a high angle, and is considerably fissured by broad deep crevasses. It has cut into the sides of the mountain a deep, narrow gorge with bare precipitous cliffs. The glacier and the valley of the Little Sandy are both quite narrow.

One of the most marked geological and topographical features of Mount Hood and the vicinity is its very extensive system of extinct glaciers, which everywhere gouged out immense troughshaped valleys, cutting down deeply into the earlier trachytic lava flows of the old volcano. The entire network of valleys were all connected with two main glaciers; that of Hood river on the north, and the Sandy on the south. The ancient White river glacier was undoubtedly very large; but, as far as my observations have yet extended, had no tributaries.

Respectfully yours,

ARNOLD HAGUE, Assistant Geologist. I propose, if my plans receive the sanction of my chief, General Humphreys, to include Mt. Baker, Mt. St. Helens and Mt. Adams and probably San Francisco Mountain, in this series of monographic surveys; if so, at the close of next summer we shall be in possession of a complete series of maps and studies of all the great isolated volcanic cones of the Western United States,

ART. XXV.-Contributions from the Laboratory of the Lawrence Scientific School. No. 13.-On some rocks and other dredgings from the Gulf Stream; by S. P. SHARPLES, S.B.

SOME time ago Mr. Pourtales gave me for analysis some specimens of bone, rock, and ooze obtained from the bed of the Gulf Stream between Florida and Cuba, while dredging under the direction of the Superintendent of the U. S. Coast Survey.

The bone was a piece of the rib of the Manatee. For comparison with this Mr. Pourtales obtained a piece of the same bone from the skeleton in the Museum of the Boston Natural History Society. He also furnished me with a number of specimens of coral from the adjacent shores.

The phosphoric acid was determined in every case, except that of the fresh bone, by means of ammonic molybdate. În the fresh bone it was determined by Rose's method with mer cury. Before treatment with the molybdate the specimen was in every case submitted to the action of the blast lamp for fif teen or twenty minutes in a platinum crucible; by this means every trace of organic matter and carbonic dioxide was expelled.

The first analysis was that of the bone; it was dark colored and almost destitute of organic matter, but still showed distinct traces of fibrous structure. Its density was much greater than fresh bone and it had become very hard. It was from the dredging of May 9, 1868, in 106 fathoms. By the side of it is placed the analysis of the recent bone, which is also calculated as free from organic matter.

The second specimen examined was a hard dark colored rock from the dredging of May 15, 1868, off Sand Key, Florida, in 100 fathoms. It was nearly free from organic matter.

The third specimen was similar to No. 2, except that it contained more organic matter and was intermixed with broken shells and coral, and appeared to be of a more recent formation. It came from the dredging of May 9th, 1868, 11th dredg ing in 116 fathoms.

No. 4 was a loose rock made up of fragments of corals and seemingly held together by calcic carbonate; it was nearly

white, contained but little organic matter and only a mere trace of iron; it was from the third dredging, May 1, 1868, in 183 fathoms. The mud in external characteristics resembles the Atlantic ooze, but differed from that examined by Messrs. Forbes and Hunter in being almost destitute of silica and ferric oxide. The silica consists almost wholly of sponge spicules.

The corals were examined mainly with reference to the amount of phosphoric acid that they contained. Silliman's analyses, made in 1846, were as good, perhaps, as the state of the science allowed at that time. He seems though to have overlooked one fact in his experiments that Berzelius long ago pointed out, that tri-calcic phosphate is soluble to a considerable extent in neutral or alkaline solutions containing organic mat

In order to confirm this fact I took a solution containing about 01 pr. ct. of glue and added to it some sodic phosphate and then calcic chloride in considerable excess and afterward calcic hydrate to decided alkaline reaction. The filtrate from the precipitate formed was evaporated to dryness and then tested with magnesium wire after Bunsen's method for phosphorus; it gave a strong reaction.

I also took about 100 grams of Madrepora palmata, treated it in the same way as Silliman did his specimens, with the exception that it was put into the acid in a single piece, thereby avoiding any contamination from the mortar. The precipitate contained a large amount of organic matter, but on testing it for phosphoric acid, it was found to be almost free from it, while the coral treated in fresh state gave a strong reaction.

My experiments failed to show more than the slighest traces of fluorine and I could only find silica in one or two instances and then in mere traces. There were also traces of iron and magnesia.

The above analyses are interesting from several points of view. In the case of the bone we have first a replacement of tri-calcic phosphate by calcic carbonate. The total percentage of lime having diminished, while iron, which was present only in traces in the original bone, exists in considerable quantity.

In regard to the replacement of the phosphate by carbonate one or two explanations may be offered. Calcic phosphate, as shown above, is soluble to a considerable extent in solutions of organic matter. This will account for the removal of part of that salt. Then again during the decomposition of the gelatine of the bone ammonic carbonate would be formed in considerable quantities. The cartilage of bone containing about 18 per cent of nitrogen which would be equivalent to about 123 per cent of ammonic carbonate, alkaline carbonates decompose calcic phosphate more or less completely; they also precipitate calcic sulphate from solution; forming in both cases calcic carbonate. We should therefore have ammonic sulphate and phosphate going into solution while calcic carbonate would be deposited.

We have now remaining only the oxide of iron to be accounted for; the silica being mostly in the insoluble state may be regarded as adventitious. It is a difficult matter in absence of any data concerning the amount of iron in the waters or bottom of the Gulf Stream or Gulf of Mexico to do any thing more than offer a possible explanation of the presence of so large a quantity of this element. Very few of the analyses of sea water give more than a trace of iron. The waters of the open ocean are almost entirely free from it. But those of inclosed seas, such as the Black and Mediterranean, contain a considerable amount. It is also contained in river water, it being absent in but few of the analyses of such water that have been given.

Now we have in the case of the Gulf of Mexico a sea that is for all practical purposes surrounded by land, and we have also large rivers carrying down in all probability great quantities of iron. This coming in contact with decomposing organic matter will be converted at first into carbonate and deposited; it will then be slowly changed into sesquioxide. This is a change that, it is admitted, is slowly going on at the bottom of most ponds.

The analysis No. 2, of rock gives an instance when this change has gone further, and the phosphoric acid has become much reduced in amount, both by the solvent action of the or