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CARRIE ADELINE BARBOUR.
Since 1891 our University has sent out annual
geological expedition--the Morrill Geological Expeditions. Three
have gone to the Corkscrew beds of Sioux county, two to the Big
Bad Lands of Dakota, and one to the rich fossil fields of Long
Island, Kans. As Nebraskans, the Corkscrew beds and their contents
have a particular interest for us, for this state alone seems to
furnish these new and strange fossils. They are embedded in soft
sand stone but it does not seem so soft to the student who works
them out with pick and spade, digging through yards of this
sandstone. However, after these spirals are secured and carefully
packed, and finally reach the tables of our workroom, the
sandstone is very dry and readily gives way before the toothed
chisel and the whisk broom. Though it may seem funny, the whisk
broom is one of our most efficient tools in cleaning Daemonelix.
Where breaks and fractures occur in these sandy specimens, it is
impossible to glue them together. Accordingly, it is necessary to
dig out large cavities and dowel them together, as it were, with
plaster of Paris.
The Bad Lands, which are old lake deposits,
consist of clays alternating occasionally with beds of sand. Now
if these clays ,were not so plastic and so easily affected by
frost-cracks, suncracks, and all oscillatory movements, the work
of collecting, cleaning, and mounting afterwards would be much
easier. As it is, fossil bones are often badly faulted. Sandstone
packs solidly, preserving the bones in a much better condition,
making, however, anything but play for the collector, and the task
of digging them out of the sand matrix is accomplished only by
careful and patient work.
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In the field, the geologist scrutinizes
every inch of these sands and clays, and upon finding so much as a
tooth exposed to view it is carefully examined and if there are
signs of a skull or mandible, either in whole or in part, or any
other good bone, the picks, spades, and drills are set to work
digging out a large block of the matrix in which the specimen is
embedded, the matrix being the best packing material in which to
ship a specimen. If much of the fossil is exposed, paper, or
sometimes cloth, is pasted over it and if it is a very heavy bone,
and unusually choice, paper, cloth, and burlap are successively
pasted upon it. Care is used not to cook the paste, but to make a
very thick batter of flour and water. The whole, when dry, is
stiff as a board, and the fossil is ready for a journey of any
distance. Sometimes a thin coating of plaster of Paris may be
added over all to advantage.
When beginning work on these specimens in the
laboratory, the paper or cloth is soaked and pulled off, then the
task of removing the matrix begins. This matrix or sandstone is of
all degrees of coherence, varying from the friable, to that of
flinty hardness. As the matrix varies from soft to hard, so the
fossils incased will vary in hardness.
The chisel and mallet are among the most useful
tools in this work, with awls of different kinds for the more
delicate bones; trowels, chisels, scrapers, and penknife for the
larger bones. The sand bag, upon which the matrix rests while we
dig out the specimen, and the sand box, in which one part of the
specimen can be firmly supported while the other parts are
attached, are indispensable to the workroom.
We will suppose the matrix removed and all ready
for joining the parts cracked by frost, or broken while removing
the hard sandstone. The very small bones can be safely united with
glue. The next larger sized bones can be satisfactorily fastened
together with plaster of Paris, using gum-water instead of water
for making the plaster. The plaster made with gum acacia,
dissolved in water, has many advantages over the ordinary plaster
as it does not harden so soon, and more time and care can be used
in joining the breaks; and when this plaster is once set it is
much
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harder and more lasting than the ordinary kind. True, the
gum acacia is expensive, but if used with care, a little will last
a long time, and it has many useful qualities. Glue water has much
the same effect, but is not quite so satisfactory, and, if used
freely, causes the plaster to crack.
And now come the large bones of the large
animals. These are much more difficult to join than the small and
medium sized bones which we have just been considering. In the
hollow limb bones, the outer portions are often hard and durable,
while the cavities are filled with calcareous material which can
easily be bored. Taking care that the holes in the pieces to be
joined correspond, insert long screws or wire and fill in with
plaster of Paris, thus making a strong joint. Again, the cavities
may be filled with material so hard that hydrochloric acid is used
to eat out the holes.
The Loup Fork Tertiary, which extends through
the western part of this state and down into Kansas, is a more
recent deposit than the Bad Lands, so the bones found at Long
Island, Kan., where the Morrill Geological Expedition collected
one summer, are very brittle as the organic matter has been
removed and the cavities have not been filled. Hence exposure to
the air often causes such bones to crumble. At best they are very
delicate specimens to handle, but they can be hardened by soaking
in gum water or glue water and drying.
In the loess, which is our most extensive
deposit and a very recent one, many fossils are found, which must
be treated in a similar manner.
Although western Nebraska is in the distinctly
sub-arid and "arid" regions, yet there is no part of the state so
arid that tuft grass instead of prairie grass grows. This tuft
grass is a distinct characteristic of the extreme arid region. In
such regions it is rather a simple matter to find exposed on the
surface between the tufts of grass such bones as may be washed out
by storms and freshets; however, in Nebraska it is a much more
complex matter to find such remains, because of the covering of
grass which practically grows over the whole state, save in the
very bad lands
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themselves. However, if such fragile bones as those of
the mastodon and mammoth--which have been so recently buried that
they are rendered brittle by the loss of their organic matter,
without replacement by calcium carbonate or silica--were exposed
on the surface they would perish immediately. Accordingly those
preserved have generally been brought to light by the plow and
scraper in preparing some cut or fill for the railroad or public
highway or for an irrigating ditch. In other cases the farmers
notice around the prairie dog holes stray bits of bones, which,
from their very texture, show that they are of organic origin, and
so arouse attention. By following the holes a sufficient distance,
the bones through which they burrowed can be rescued. In this way,
by following the windings of a prairie dog burrow for nearly forty
feet through the loess formation in Buffalo county, one of the
tusks in the State Museum was recovered, together with fragments
of other bones. The particularly fine pair of tusks, which are
scarcely rivaled by any better representatives in any museum, were
found in a railroad cut along the Burlington and Missouri River
railroad in Gosper county.
At this particular spot the loess is very thick,
and being subject to considerable surface erosion, it is cut in
all directions by various drainage lines, so that the whole region
is crossed by rather sharp draws, bordered by hills of yellow
bluff soil. The railroad made a cut through one of these hills
amounting to several hundred yards in length, and from fifty to
sixty feet in depth. The material excavated in the cut was shipped
forward a distance of a mile or two to make an extensive fill. The
workmen said that "they had never plowed and scraped through such
remarkable bones." The scraper and plow cut through thigh bones,
vertebrae, ribs, scapula, and skull, bringing them to the surface
where they were much admired for their size and beauty, but for
all that they were carried to the dump and forever destroyed. The
plow and scraper went mercilessly and merrily on, until it had
entirely destroyed the skeleton, the skull, and two to three feet
of the great tusks. But the work of destruction was not to end
there, for the workmen after that amused themselves
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by reaching in at the side of the bank and pulling out handsful of the friable bony matter of the tusk. This being incompletely fossilized, and having been subject to the action of frost and the force of growing rootlets, was shattered into innumerable small bits, so that the once hard ivory could now be picked away by the handful. Every scrap of tusk was entirely picked away as far in as the arm could reach. The work of destruction would have gone still farther if it had not involved some labor. The railroad men reported this specimen to a local doctor, who immediately decided to rescue the tusks for his private collection; accordingly he dug quite a ditch in such a way that it would cross about the middle of the left tusk. It may be explained here that the two tusks laid quite as they did in life. At this point he cut out as much as he could without broadening his ditch; finding it was simply so many fragments in his hands, it occurred to him that very likely the tusk was more solid at the tip. Accordingly he dug a second trench near the tip, and there destroyed nearly three feet more of this excellent specimen. Fortunately, while he dug away everything else, he did leave the hole where the tusk laid; accordingly it was not a very difficult matter to fill in these places with plaster of Paris, and so preserve with actual fidelity the shape, size, sweep, and length of the tusk. The holes in the bank where they had reached in and dragged out handsful of the ivory had suffered very little from several months of the weathering; these were likewise filled with the plaster of Paris and then the work of excavation began. They were overlaid by about five or six feet of the loess, which is soft and extremely easy to dig with the spade or shovel. However, during the entire time of excavation a fierce gale of wind was blowing, which carried so much fine sand that it was with extreme difficulty that the work could be carried on. As soon as a surface was laid bare on the tusk the wind immediately carried away pieces of the ivory--which was arranged in concentric layers; accordingly it was necessary not to expose more than two to three square inches at a time and to promptly paste over this a layer of paper, then expose a few inches more and paste that with
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paper. In this way both tusks were dug out and laid bare to the action of the sun and wind. This done, it was found necessary to paste cloth over the tusks and around them in all directions, so as to give it sufficient "body" to hold the fragile parts in place until it could be shipped. Both tusks were allowed to stand on stilts of the original clay in which they were imbedded, but these had to be replaced by wooden stilts, in order that all of the surface might be pasted with paper, cloth, and burlap. The next thing was to pull up large masses of stiff grass, which grew in a marshy spot near by. These tufts of grass were arranged longitudinally along the tusks and wrapped and tied very securely in place by means of binding twine. On top of all was bound a heavy layer of stout willow sprouts in order to give it additional stiffness and strength. However, in spite of all these precautions, it was found to be entirely impracticable to lift or move these tusks in any way. The only possible means of rescuing them was to build a large crate about them as they lay in position and to suspend each tusk by means of rope and twine. In this position, when sufficiently roped, it was an easy matter to pick up crates and specimens and carry them down the hill and deliver them at the nearest station, some nine or tell miles distant. The boxes when done were so large that it was found impossible to get them in side of an ordinary wagon and considerable embarrassment was experienced for a time. Finally, however, they were roped on top of the wagon, extending across it, and in this way were safely transported to their destination. The tusks were driven across a very rough prairie, part of it without roads or trails, a distance of nine or ten miles, then shipped by railroad from Gosper county to Lincoln, and delivered at the museum still swinging by cords and ropes and without breakage or injury. Then began the work of unpacking and preparing the specimen in some permanent way. The burlap, cloth, and paper were re moved, a few inches at a time, and a mixture of paraffine (sic), beeswax, and resin was melted and poured over the exposed part. This melted mixture sank in-to every crack and upon cooling hardened and united the parts completely. Finally, holes were bored
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a long the sides, about four inches apart and as deep as the center of the tusks. In these hot wax was poured. This strengthened the tusks to such an extent that they could be handled with safety preparatory to mounting them upon permanent bases of plaster of Paris, such as they now stand upon.
EXPLANATION OF FIGURE 1.
Two tusks of the mammoth or primitive elephant partly uncovered. Found in the loess of Gosper county, Nebraska, on the face of an extensive cut on the Burlington & Missouri River railroad. Length of tusk along the curve, 11 feet; diameter at base, 7 inches. From a photograph by Erwin H. Barbour, Morrill Geological Expedition, 1893,
© 2000, 2001 for NEGenWeb Project by Pam Rietsch, T&C Miller