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your work you will return to Washington, the route being left to your discretion, to be determined by considerations which cannot now be foreseen: Very respectfully,
G. K. GILBERT,
Chief Geologist. Approved,
J. W.. POWELL, Director.
DEPARTMENT OF THE INTERIOR,
Washington, D. C., May 28, 1890. Mr. Mark B. KERR, Disbursing Agent.
Sır: You are hereby detailed to assist Mr. I. C. Russell, Geologist, who starts at once on an expedition to Alaska, under the joint auspices of the National Geographic Society and the United States Geological Survey. It is expected that you will immediately aid him in disbursement, and that you will act during the exploratory part of the expedition as topographer. Your duties will, however, not be limited to these special functions, but you will be expected to perform any other duties he may assign to you, and to labor in every way for the success of the expedition.
It is expected that you will be reappointed to the grade of topographer on the United States Geological Survey on the 1st of July, 1890, and you will please take the required oath of office before your departure.
The money remaining in your possession as Disbursing Agent includes that needed to meet Mr. Russell's salary and your own, and also the sum of $1,000, allotted from the funds of the Geographic Branch for expenses of the expedition prior to June 30. This amount you will expend as directed by Mr. Russell, and his authority and certificate will need to accompany your vouchers in rendering account of the same. Very respectfully,
G. K. GILBERT,
Chief Geologist. Approved,
J. W. POWELL, Director.
DEPARTMENT OF THE INTERIOR,
Washington, D. C., May 28, 1890. Mr. MARK B. KERR,
Disbursing Agent. Sir: You will proceed at once to San Francisco, California, and thence by steamer or by rail and steamer to Sitka, Alaska. It is expected that you will join Mr. I. C. Russell, Geologist, at Victoria, B. C., or at Sitka; and you will report to him for further orders. Very respectfully,
G. K. GILBERT,
Chief Geologist. Approrrd,
J. W. POWELL, Director.
Washington, D. C., May 29, 1890. Mr. Mark B. KERR, Topographer.
Sir: You are hereby assigned to field-work in the vicinity of Mount St. Elias, Alaska, in the party under charge of Mr. I. C. Russell. Upon the receipt of these instructions you will please proceed without delay to the field, and map upon a scale of four miles to an inch such territory in the vicinity of Mount St. Elias, including that mountain, as the field season will permit. The work should, if practicable, be controlled by triangulation. Special attention in the course of your work should be given to measuring the altitude of Mount St. Elias, and it should be determined by triangulation and also, if practicable, hy barometer in such manner as to be conclusive.
The topographic work should be controlled by triangulation. As many positions on this coast are approximately known, including a number of the prominent peaks, astronomical determinations of position will not be necessary unless needed to supplement the triangulation.
The details of your outfitting and the management of the work will be left to your own judgment. Very respectfully,
NATIONAL GEOGRAPHIC SOCIETY.
Vemorandum of Instructions to the Party sent out under the Direction of Mr.
I. C. Russell, assisted by Mr. Mark B. Kerr, to explore the Mount St. Elias Region, Alaska, 1890.
The general object of the expedition is to make a geographic reconnoissance of as large an area as practicable in the St. Elias range, Alaska, including a study of its glacial phenomena, the preparation of a map of the region explored, and the measurement of the height of Mount St. Elias and other neighboring mountains. Observations should also be made and information collected on other subjects of general scientific interest as far as practicable.
The purpose of these instructions is mainly to suggest the lines of investigation that give promise of valuable results, but it is not intended that they shall limit the director of the expedition in the exercise of his own discretion.
GARDINER G. HUBBARD, Chairman,
REPORT ON TOPOGRAPHIC WORK.
BY MARK B. KERR.
In addition to the ascent of Mount St. Elias, it was part of the original plan of the expedition to make an accurate topographic map of the region explored. It was not, however, for this purpose proposed to divide the party or to deviate much from the most direct route to Mount St. Elias from Yakutat bay. Triangulation of fair precision was provided for. Details were to be filled in by approximate methods.
Field-work began June 20 by the careful measurement of a base-line, 3,850 feet in length, near the point of landing, on the northern shore of Yakutat bay. Expansion was readily carried to the foot-hills, and several horizontal angles were taken to an astronomical station of the United States Coast and Geodetic Survey at Port Mulgrave. In the region of these initial triangles, work was done from a central camp; and topographic details were fixed with considerable precision by intersection and vertical angles.
After the departure of the expedition from the Base Line camp, an accident to the transit made resort to an inferior instrument necessary, and, furthermore, as the region traversed proved to be ill-adapted to, and the line of travel too direct for, the proper development of a narrow belt of triangles, the anticipation of a degree of precision in the triangulation which would give high value to the determinations of position and altitude of the several peaks was not realized; but topographic map work, showing the general features, altitudes and location of the mountain ranges, valleys and glaciers, was extended over about 600 square miles.
Within the approximate geometric control, stations were interpolated by the three-point method, and minor locations were multiplied by intersection and connected by sketch. The best meander possible under the circumstances was carried forward on the line of travel by compass directions and estimates of distance from time intervals. The work ceased August 22 with the abandonment of the instruments in a snow-storm of four days' duration on the eastern slope of Mount St. Elias.
The accompanying map (a reduction of which forms plate 8, page 75) shows the ice-streams and peculiar mountain topography of a region heretofore unvisited, and constitutes a considerable addition to the geography of Alaska.
REPORT ON AURIFEROUS SANDS FROM YAKUTAT BAY.
BY J. STANLEY-BROWN.
Among the specimens obtained by Mr. I. C. Russell during the course of his explorations on and about Mount St. Elias is a bottle of sand procured from the beach on the extreme southern end of Khantaak island, Yakutat bay, and characteristic of the shore material over a large area. This sand was turned over to me for examination, and additional interest was given to its study by the fact that it is from a comparatively uninvestigated region and possesses, perhaps, economic value; for the sample is gold-bearing, and it is said that a “color” can readily be obtained by “panning” at many points on the bay shore.
Macroscopically, the sand has the appearance of ordinary finely comminuted beach material; but it differs in the uniformity of the size of its particles from beach sand from Fort Monroe and Sullivan island, South Carolina, with which it was compared. Its mineralogic constituents greatly surpass in variety those of the sands referred to, but are markedly similar to those of gold-bearing sand from New Zealand. At least twelve minerals are present, with an unusual predominance of one, as will be noted later. Through the mixture of white, green, and black grains, a dull greenish-black color is given to the mass. The roundness of fragments is such as usually results from water action, but it is less than that which results from transportation by wind.
When put into a heavy liquid (Thoulet solution of a density of 3.1) in order to determine the specific gravity of the constituents, it was found that the sand is made up largely of the heavier materials, for the amount that floated was trifling compared with that which quickly sank. Even the abundant quartz was largely carried down by the weightier ingredients bound up within it, and only a few water-clear fragments were left behind. This would seem to suggest that the lighter minerals are lacking in the neighboring rocks, or else have been carried to greater distances by the sorting power of the water.
Among the minerals recognized, gold is the most important, though relatively not abundant. It occurs in flakes or flattened grains from a quarter to a half of a millimeter in size. The particles are sutficiently numerous to be readily selected from their associates by the aid of “panning” and a hand lens of good magnifying power, and if distributed throughout the beach as plentifully as in the sample would, under favorable conditions, pay for working. The flakes in their rounded character show the effect of the agency which separated them from their matrix; a separation so complete that no rock is found adhering to the grains.
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 tt per cent. of this fine material. Crystallographic faces are rare, and though often marred, still oclahedrons (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 note: 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. (rystallographic 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 hy 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 suflicient 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 hear 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, and rice
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 ditferent 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.
27 - NAT. GEOG. MAG., VOL. III, 1891.