Part 2 — APPENDIX.—ON THE COLLECTION AND PRESERVATION OF FOSSILS.

The tools and other paraphernalia necessary for fossil collecting are fortunately within the reach of all. The principal of these is a geological hammer, preferably with a pick at one end of the head and the opposite end square-faced. The pick end is useful for digging out fossils from soft clays, or for extracting a block of fossils entire. The square end is employed for breaking up the slabs or masses containing fossils. To get good results, much will of course depend upon one’s skill in striking the right face of a block. If bedding planes are present on the lump from which we wish to extract our fossils, it will be well to strike at right angles to these layers in order to split them asunder, thus exposing a shell-layer corresponding to the original surface of the ancient sea-bed upon which the organisms accumulated. In some cases the splitting of fossiliferous rocks may be best carried out with the pick end, provided it be not too sharply curved. The hammer should be faced with steel, for many fossiliferous rocks, especially compact limestones, are apt to severely try the temper of an ill-made tool.

A chisel, of chilled steel, should accompany the hammer, since this is often of the greatest use in working out large fossils, more particularly those that are buried in a cliff or quarry face. The process of extracting difficult specimens should never be hurried, for one often gets surprisingly good results with a little extra care.

A strong pocket knife may be used in trimming specimens and partially cleaning shells that can be safely manipulated on the spot, but the final cleaning should be left until the return home. The knife is also useful for cleaning slates and shales, since the chisel-edge is frequently a trifle too thick for this kind of work.

For the more delicate fossils, means for careful packing should be provided; chip-boxes and cotton-wool being indispensable for the smaller specimens. A ready method of packing the fossils obtained from the friable, sandy tertiary deposits is to store them in tins, the contents of which can be firmly secured from rattling by filling up with sand. This sand, however, should be taken from the same bed in which the fossils occur, so as to get no admixture of the smaller shells from another formation or deposit; for although we may not wish to examine the finer material ourselves, it will yield in many cases a rich harvest to our microscopical friends, such residues containing microzoa, as shells of foraminifera, polyzoa and carapaces of the ostracoda. The residues referred to may be obtained from many of our marls and rubbly limestones by the simple process of washing in water, and repeatedly pouring off the finest clayey mud, until only a sandy deposit remains, which can then be dried and sorted over by the aid of a lens or low power microscope.

Hints on Fossil Collecting.—

As regards the places most suitable for collecting fossils, the Cainozoic beds are perhaps, the most accessible to a beginner, especially in Victoria. For instance, the cliff exposures at Beaumaris, Port Phillip, will afford a plentiful supply of the little heart-shaped sea-urchin, Lovenia, and an occasional Trigonia and Limopsis, as well as many other fossils of the great group of the shell-fish or mollusca. The richest bed containing the sharks’ teeth at the above locality is almost perpetually covered with a bed of shingle, but can be reached by digging at the cliff-base. Isolated specimens, however, although rather the worse for wear, may often be picked up amongst the shingle, having been washed up from the foreshore by the tide. An enticing band of large bivalve shells (Dosinea), can be seen halfway up the cliffs, near the baths at this locality, but are somewhat disappointing, for when obtained they crumble to pieces in the hand, since their shells are composed of the changeable form of carbonate of lime called aragonite, which has decomposed in place in the bed, after the shells were covered up by the deposit.

Good collections of shells of the Balcombian series may be easily made at Balcombe’s Bay and Grice’s Creek, Port Phillip. They can there be dug out of the grey-blue clay with a knife, and afterwards cleaned at leisure by means of a soft tooth brush dipped in water. In the cement stone at the same place there are numerous shells of pteropods or “sea-butterflies” (Vaginella), and specimens of the stone may be obtained, showing myriads of the porcelain-like shells, and also their internal casts in the hard greenish coloured matrix.

The ferruginous or ironstone beds seen in the Flemington Railway cutting, Melbourne, is an old marine shell-bank, resting on basalt. The shells have all been dissolved away, and only their casts and moulds remain. These impressions are, however, so faithfully moulded that the ornamentation of each shell can often be reproduced on a squeeze taken with a piece of modelling wax or plasticine. Such fossil remains are easily collected by carefully breaking up the blocks of ironstone with a hammer.

Quarries in the older limestones and mudstones in Victoria, New South Wales and other States, are often good hunting grounds for fossils. The quarry at Cave Hill, Lilydale, for example, will be found very profitable, for the limestone is full of corals and molluscan shells; whilst the friable or rubbly portion is worth breaking down for the smaller fossils. The bed-rock (Silurian) of Melbourne is in places very fossiliferous; the sandstones of Moonee Ponds Creek generally affording a fair number of brachiopods, and occasionally corals. The mudstones of South Yarra, Studley Park, Yan Yean, and other places on the same geological horizon, contain a rich fauna, to be obtained only by the assiduous collector who will search over and break up a large number of blocks. Practice in this work makes a good collector; although of course one must know something about the objects looked for, since many apparently obscure fossil remains of great interest might easily be passed over for lack of knowledge as to what should be expected to occur at each particular locality.

Many other good collecting grounds might here be alluded to, but we have purposely cited only a few near Melbourne, since a selection from other parts of Australasia may easily be made from the localities mentioned in connection with the various groups of fossils dealt with in the systematic portion of this work.

Preservation of Fossils.—

Many of the Cainozoic fossils from the shelly sands and clays are extremely delicate, owing in some cases to their being imperfectly preserved, seeing that they frequently contain in their shell-structure layers of the unstable form of carbonate of lime called aragonite. Fossils containing aragonite are:—Calcareous Sponges; Corals; Bivalved shells, except Oysters, Pectens, and the outer layer of Spondylus, Pinna, and Mytilus; Gasteropods (with a few exceptions); and Cephalopods. In some of these, however, a transformation of the aragonite into calcite enables the fossil to be permanently preserved. The delicate fossils referred to should be dipped in weak glue or gelatine and left to dry; after which their final cleaning can be done with the aid of a little warm water and a soft brush.

Certain of the clays and mudstones, both of Cainozoic and Jurassic ages which show remains of plants, such as leaves and fern fronds, are often best treated with a thin surface layer of paper varnish, before they lose the natural moisture of the rock; for when they become perfectly dry the thin carbonaceous film representing the original leaf-substance peels off, and the fossil is consequently destroyed. A method of treatment for Cainozoic leaves, by dipping them in warm vaseline and brushing off the superfluous material, has been described by Mr. H. Deane.

Storing Fossils for Reference.—

Fossils specimens are generally best displayed in cardboard trays; or if thin wooden paper-covered tablets are used, say of about 3-16in. thickness and cut to proportionate sizes, the fossils should be held in place by pins for easy removal, unless more than one example can be shown together, exhibiting all aspects, when they can be secured to the tablet by a touch of seccotine. The smaller shells may be displayed in glass topped boxes, which in turn may be stuck down to tablets or placed in trays.