THE DEPARTMENT OF GEOLOGY OF THE U. S.

NATIONAL MUSEUM.

By GEORGE P. MERRILL.

[With 20 plates.]

INTRODUCTION.

The Geological Department, as an integral part of the National Museum, dates from the appointment of Dr. George W. Hawes as curator, in 1880, after the completion of the brick building on the south side of the Smithsonian grounds, now occupied by the Department of Arts and Industries. Prior to this time, owing to the limited amount of space that could be devoted to Museum purposes in the Smithsonian Building, collections were necessarily small and development impossible. At the time Doctor Hawes entered upon his duties as curator, he also assumed charge of that branch of the Tenth Census relating to the quarry industry, and to this he devoted a large share of his attention during the brief period of his incumbency. To the Centennial Exposition of 1876, the United States Land Office and the various United States geological surveys and exploring expeditions, the department is largely indebted for whatever material it possessed prior to the date mentioned. Since that time the administration has undergone various changes, and the entire department moved from the brick building on the south side of the grounds to the new granite Natural History Building on the north side. The present paper is intended as an outline guide to the collections, and as well, to show the scope of the department and to what extent it is fulfilling its part as a Government repository for materials of scientific interest and value. The chief sources of its material, it may be well to add, are the various bureaus of the Government (particularly the United States Geological Survey), which by law are directed to deposit in the National Museum all collections " when no longer needed for investigations in progress."

With reference to the arrangement of the exhibits, it may be well to state that the space assigned to geology is not such as to make a strictly systematic arrangement of the collections desirable or practicable. Certain halls are best adapted to the exhibition of a particular class of material and quite unsuited for others. A collection

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of small objects, for instance, would be quite lost in the large main hall on the ground floor, although it is admirably adapted to the use to which it is now put-that of an exhibit of fossil vertebrates. As here described, the visitor enters this hall from the rotunda at its western end, with the side halls on the south and north devoted to invertebrate fossils and fossil plants. Thence one passes northward into the east range devoted to physical and chemical geology. Returning to the rotunda once more and proceeding to the second floor, the mineral collections will be found on the south side of the east wing and, at the east end and on the north side of this same wing, the collections of ores and other material of economic interest. Expressed in tabular form, and as shown by the diagrams (fig. 1 and 2) the order of arrangement is as follows:

First floor

Fossil invertebrates, east wing, south side.

Fossil vertebrates, east wing, center and east end.

Fossil plants, east wing, north side.

Physical and chemical geology (including petrology and meteorites), east range.

Second floor

Minerals, gems, and precious stones, east wing, south side.

Economic geology, east wing, east end, and north side.

It may be well to state here, that the value of geological material for purposes of study and research is as a rule but slightly dependent upon its value for exhibition purposes. Hence it follows that a very considerable proportion of the collections is stored away in drawers, inaccessible to the general public, but available for study to any properly accredited student. The specimens thus stored away, constituting what is known as the study series, run numerically in hundreds of thousands, or even millions if the smaller invertebrate fossils are considered individually. Many of these are types, i. e., are the identical specimens "used by the author of a systematic paper, as the basis of detailed study, and as the foundation of a specific name." As long ago as 1905 there were in the division of invertebrate fossils alone some 11,490 types representing 6,100 species 1 and at the present time there are probably at least twice that number. Some of the more important of the collections in this study series are enumerated on pp. 269-271.

DIVISION OF PALEONTOLOGY.

SECTION OF INVERTEBRATE FOSSILS, EAST WING, FIRST FLOOR.

In this division the exhibits are arranged in three definite series: (1) a stratigraphic series, in the long continuous case along the

See catalogue of the Type and Figured Specimens of Fossils, Minerals, Rocks, and Ores in the U. S. National Museum, Bull. 53, U. S. N. M., 1905.

WEST RANGE

public which may have little interest in scientific names and technical descriptions. Therefore the usual labels giving only the scientific name and locality of various forms on exhibition are here replaced by brief descriptions of the specimens in plain English. For

WEST COURT

NORTH PAVILION

SCALE

WEST WING

NORTH WING

EAST RANGE

north wall; (2) a biologic series, along the south wall in separate cases, each of which is devoted to some special class of animals; and (3) a line of large exhibits, through the center of the hall, illustrating the various phenomena connected with the formation of stratified rocks and their contained fossils.

Each of these three series is arranged primarily for a general

interest, each of which illustrates some definite chapter in the earth's history, will perhaps be most attractive to the majority of visitors (pl. 2, fig. 1). Near the entrance, as an example, is a slab of Cambrian sandstone, mounted as it was quarried out of the solid rock, and

the benefit of the scientific visitor the technical names are introduced in a subordinate position.

Geological phenomena.-The line of exhibits through the center of the hall comprising large objects of geological and paleontological

representing the solidified sand of a very ancient sea beach. Besides preserving the original ripple marks, it is crisscrossed by tracks not unlike those of an automobile tire but in reality representing the impressions left upon the sea beach by a large wormlike animal. Following this fossil sea beach is a base containing slabs of shale, sandstone, and coralline limestone, each crowded with fossil remains and representing types of near-shore sedimentation. Nearby is a mount of conglomerate, a type of rock in which fossils are less often found. Each of these tells its own story. One specimen, the "edgewise" conglomerate, is a fragment of a formation 3,000 feet thick, extending throughout the Appalachian area and made up of slivers of limestone standing on edge. Another has a different history, as it is composed of rounded quartz boulders. A third contains only angular boulders of limestone forming a "breccia," while still another is a consolidated mass of scratched glacial pebbles.

Near at hand is a large slab of Devonian limestone composed entirely of the stems and calices of a species of gigantic fossil sea lily. This slab formed part of a layer outcropping along the bluffs of the Mississippi River south of St. Louis, Mo. Passing other exhibits in this series, attention may be directed to a limestone slab of considerable size showing a stratigraphic unconformity, or expressed otherwise, affording an actual illustration of the dividing line as registered in the rocks, between two great periods of the earth's history. Nearby are large masses of limestone showing the ancient plant and animal remains to which they owe their origin. Another large rock fragment illustrates the formation of the wellknown fertilizer, calcium phosphate, from small phosphatic shells. The differences between the faunas or assemblages of animal life in the different geological periods is shown by two exhibits.

The first, from the Frank Springer collection, is a fragment of a Cretaceous sea bottom exhibiting a colony of fossil crinoids (Uintacrinus socialis Grinnell). The slab (pl. 3, fig. 1) is 7 by 8 feet in diameter and is the remnant of a lenticular plate, originally upward of 50 feet in diameter, composed of the remains of a large colony of these free-floating organisms, which swam vigorously by means of their long arms. They frequently collected in dense swarms with arms and pinnules intertwined, and thus perished, the entangled mass sinking to the bottom, where, as in this case, it was flattened and embedded in the soft mud. With time and pressure the mass became consolidated into a thin plate of limestone, with the crinoids well preserved on the under surface. This, after being lifted out of the quarry, and freed from the fine adherent matrix, is now exposed to view. Nearly all of this colony was destroyed by erosion before its discovery, and the parts recovered were necessarily more or less fractured, but the