Magnetite is present in great abundance and in a finely divided state, the largest grains not exceeding a millimeter in length. It forms by weight alone 15 or 20 per cent. of the entire mass, and when the latter is sifted through a sieve of a hundred meshes to the inch it constitutes 44 per cent. of this fine material. Crystallographic faces are rare, and though often marred, still octahedrons (111, 1) of considerable perfection are found.
Garnet occurs in such profusion that a pink tint is given to a mass of selected grains of uniform size, and its predominance may be considered the chief physical characteristic of the sand.
Two species were noted: one is a brilliant wine-red variety, which, though not nearly so numerous as its duller relative, occurs more frequently in crystals—the trapezohedral faces (211, 2–2) predominating. The other garnet is readily distinguished by its lighter amethystine tint and its greater abundance. Crystallographic faces are somewhat rare and invariably dodecahedral (110, i). In the absence of chemical analyses, any statements as to the exact species to which these garnets should be referred would be largely conjectural. Attention is quickly drawn to the perfection of these minute garnets in their crystallographic faces and outlines, and to their association with rounded fragments of their own kind as well as of other minerals. Have these crystals survived by reason of their hardness or by favoring conditions, or does their preservation suggest the impotency of wave-action in the destruction of minute bodies?
Among the black, heavy grains occur individuals which, except in shape and non-magnetic character, resemble magnetite. On crushing between glass slides, thin slivers are obtained which in transmitted light are green, and which, from their cleavage, pleochroism, high index of refraction, small extinction angle, and insolubility in acid, are readily recognized as hornblende.
Two groups of grains were noted which are distinguishable by slight variation in color. Both are clear-yellowish green, but one is somewhat darker than the other. The optical properties of both indicate pyroxene and possibly olivine. Fortunately a fragment was obtained in the orthodiagonal zone nearly normal to an optic axis which gave an axial figure of sufficient definiteness to indicate its optically positive character. A number of grains were selected from minerals of both colors and subjected to prolonged heating in hydrochloric acid without decomposition, indicating that both minerals are pyroxene.
A few zircons, a fraction of a millimeter in size but perfect in form, were found associated with others rounded on their solid angles and edges. The crystals are of the common short form and bear the usual faces in a greater or less degree of development. Pyramids of the first and second order alternate in magnitude; pinacoid encroaches upon prism, andvice versa.
Quartz constitutes by far the largest proportion of the minerals, both in bulk and in weight. It is always fragmental; sometimes water-clear, but chiefly occurs in opaque grains of different colors. It is seldom free from material of a higher specific gravity, and is often so tinted as to be almost indistinguishable from magnetite, but readily bleaches in acid.
Feldspar is sparingly present, and includes both monoclinic and triclinic forms, whose crystallographic boundaries are invariably lacking.
Treatment of the sand with dilute acid produces effervescence, which is not due to incrustations of sodium carbonate. By persistent search among particles separated in a heavy solution, a few grains were discovered which, from their complete solubility with effervescence in very dilute acid, as well as their optical properties, left no doubt as to their being calcite.
The mica group has only one representative, biotite, and this occurs most sparingly. Though much of the sand was examined, but few fragments were found. Its foliated character renders it easily transported by water and explains its absence from among the heavy minerals.
Shaly, slaty and schistose material forms the major part of the coarser grains. Thin sections from the largest pieces plainly indicated hornblende schist.
A region of glaciers would seem to be favorable not only to the collection of meteoric material, but also to the destruction of the country rocks, the setting free of their mineralogic constituents in a comparatively fresh state, and their transportation to the sea. It was hoped that this sand would yield some of the rarer varieties of minerals, but tests for native iron, platinum, chromite, gneiss, and the titaniferous minerals proved ineffectual. Titanium is present, but in such small quantities that it could only be detected by means of hydrogen peroxide. The use of acid supersulphate and the borotungstate of calcium test of Lasaulx failed to reveal the presence of native iron.
It will be seen from the foregoing enumeration that the sand is made up of grains of gold, magnetite, garnet, hornblende, pyroxene, zircon, quartz, feldspar, calcite and mica, associated with fragments of a shaly, slaty and schistose character. While the information at hand is hardly sufficient to warrant much speculation concerning the rock masses of the interior, still there is no doubt that the sand is derived from the destruction of metamorphic rocks.
BY LESTER F. WARD.
BY LESTER F. WARD.
DEPARTMENT OF THEINTERIOR,UNITEDSTATESGEOLOGICALSURVEY,Washington, D. C., March 12, 1891.
Mr. I. C. RUSSELL,United States Geological Survey.
MYDEARSIR: The following report upon the small collection of fossil plants made by you at Pinnacle pass, near Mount St. Elias, Alaska, and sent to this division for identification has been prepared by Professor F. H. Knowlton, who gave the collection a careful study during my absence in Florida. Previous to going away I had somewhat hastily examined the specimens and seen that they consisted chiefly of the genusSalix, some of them reminding me strongly of living species. I have no doubt that Professor Knowlton's more thorough comparisons can be relied upon with as much confidence as the nature of the collection will permit, and I also agree with his conclusions.
"The collection consists of seven small hand specimens, upon which are impressed no less than seventeen more or less completely preserved dicotyledonous leaves.
"These specimens at first sight seem to represent six or eight species, but after a careful study I think I am safe in reducing the number to four, as several of the impressions have been nearly obliterated by prolonged exposure and cannot be studied with much satisfaction.
"The four determinable species belong, without much doubt, to the genusSalix. Number 1, of which there is but a single specimen, I have identified withSalix californica, Lesquereux, from the auriferous gravel deposits of the Sierra Nevada in California.38The finer nervation of the specimens from the auriferous gravels is not clearly shown in Lesquereux's figures, nor is it well preserved in the Mount St. Elias specimens; but the size, outline, and primary nervation are identical.
"Number 2, of which there are six or eight specimens, may be compared withSalix raeana, Heer,39a species that was first described from Greenland and was later detected by Lesquereux in a collection from Cooks inlet, Alaska.40The Mount St. Elias specimens are not very much like the original figures of Heer, but are very similar, in outline at least, to this species as figured by Lesquereux.41They are also very similar tosome forms of the livingS. rostrata, Richardson, with entire leaves. It is clearly a willow, but closer identification must remain for more complete material.
"Number 3, represented by four or five specimens, is broadly elliptical in outline, and is also clearly aSalix. It is unlike any fossil form with which I am familiar, but is very similar to the livingS. nigricans, For., var.rotundifolia, and to certain forms ofS. silesiaca, Willd. The nervation is very distinctly preserved, and has all the characters of a willow leaf.
"Number 4, represented by three or four very fine specimens, is a very large leaf, measuring 13 cm. in length and 3½ cm. in width at the broadest point. It may be compared withSalix macrophylla, Heer,42but it cannot be this species. It is also like some of the living forms ofS. nigra, Marsh., from which it differs in having perfectly entire margins.
"While it is manifestly impossible, on the basis of the above identifications, to speak with confidence as to the age or formation containing these leaves, it can hardly be older than the Miocene, and from its strong resemblance to the present existing flora of Alaska it is likely to be much younger." [F. H. Knowlton.]
Very sincerely yours, LESTERF. WARD.
38Mem. Mus. Comp. Zool., vol. VI, no. 2, 1878, p. 10, pl. i, figs. 18–21.
39Flor. foss. Arct., vol. I, 1868, p. 102, pl. iv, figs. 11–13; pl. xlvii, fig. 11.
40Proc. Nat. Mus., vol. V, 1882, p. 447.
41loc. cit., pl. viii, fig. 6.
32Tert. Fl. Helv., vol. II, 1856, p. 29, pl. lxvii, fig. 4.
Admiralty bay,
56
Agassiz glacier, Ascent of,
147
— — named,
73
Age of St. Elias range,
175
Alpenstocks, Necessity for,
165
Alpine glaciers,
176
,
180
Alton, Edmund, Contributions to exploration fund by,
75
Archangelica
, Mention of,
89
,
114
Atrevida
(The), Mention of,
63
Arevida glacier,
92
,
105
Auriferous sands,
196
,
197
,
198
Avalanches,
145
,
155
Baie de Monti,
56
— named by La Pérouse,
60
Baker, Marcus, Explorations by,
70
,
72
— reference to bibliography by,
58
Base Line, Measurement of,
86
Bear, Meeting with,
94
,
109
Belcher, Sir Edward, Explorations by,
68
,
69
Bell, A. Graham, Contribution to exploration fund by,
75
Bell, Charles J., Contribution to exploration fund by,
75
Bering bay, Mention of,
56
Bering, Vitus, Explorations by,
58
Bien, Morris, Contribution to exploration fund by,
75
Birnie, Jr., Rogers, Contribution to exploration fund by,
75
Black glacier, Brief account of,
101
,
104
Blossom island, Description of,
113
,
122
Boursin, Henry, Mention of,
79
Broka, George, Explorations by,
73
,
74
Camp hands,
166
Carpenter, Z. T., Contribution to exploration fund by,
75
Carroll, Captain James,
78
Cascade glacier named,
144
Chaix hills named,
73
Chariot, The, Mention of,
140
Chatham, Mention of,
66
Cherikof, Alexei, Explorations of,
58
Christie, J. H., Member of expedition,
76
— Work of,
82
,
83
,
84
,
96
,
103
,
112
,
113
,
123
,
162
Clover, Richardson, Contribution to exploration fund by,
75
Cook, Captain James, Explorations of,
58
Corwin
(The) in Disenchantment bay,
100
— Return of,
163
Crevasses,
181
,
182
— at Pinnacle pass,
130
Cross sound, visited by Vancouver's expedition,
67
Crumback, J. H., Member of expedition,
76
— Work of,
96
,
103
,
122
,
125
,
129
,
131
,
135
,
137
Dagelet, M., Mention of,
60
Dall, W. H., Explorations by,
70
,
72
— reference to bibliography by,
58
Dalton, John, glacier named for,
98
— mention of,
73
Definition of formations in St. Elias region,
167
Desengaño bay, named by Malaspina,
63
Digges' sound, named by Vancouver,
68
Diller, J. S., Contribution to exploration fund by,
75
Dip at Pinnacle pass,
140
Discovery
(The), Mention of,
66
Disenchantment bay, Canoe trip in,
96
,
103
— — last view of,
163
— — mention of,
56
— — visited by Malaspina,
63
,
64
Dixon, Captain George, Explorations of,
60
,
62
De Monti bay, Arrival at,
79
Descubierta
(The), Mention of,
63