DIRECTIONS FOR COLLECTING SPECIMENS OF GEOLOGY AND MINERALOGY.

New Zealand Spectator and Cook's Strait Guardian, Volume VII, Issue 631, 20 August 1851, Page 4

DIRECTIONS FOR COLLECTING SPECIMENS OF GEOLOGY AND MINERALOGY.

The following short directions being intended for the use of such persons as are supposed to be entirely unpractised in geology and mineralogy, all technical terms, the understanding of which presupposes an acquaintance with those sciences, have been carefully avoided; as likewise, all references to the relative order of superposition of rocks, ■and the succession in which many of the materials to be collected are known to be disposed with respect io each other. 1. Common boulders, rolled pieces of rocks or their fragments, pebbles, &c., picked up at random, in situations of no peculiar interest, are very seldom of any scientific utility; they had much better be left where they are than made the source of embarrassment to those who are expected to arrange and incorporate them with objects of systematic geological or mineralogical collections. But boulders, rolled pieces, rubble stones, and even gravel, sand, silt, and other loose materials, may prove objects of real scientific importance to the intelligent, although unscientific observer, in proportion as the nature and mode of their occurrence are ascertained, or appear to him to be connected with interesting circumstances, and questions;—such as their probable origin,—whether they may be considered as gradually washed down from higher levels by rains, rivers, &c., or as remnants of broken up beds of lakes or seas, (for both kinds have often been indiscriminately called alluvial,) &c., —and he will often find them to contain many interesting remains, teeth, and other bones, of elephants, hippopotamus, rhinoceros, petrified wood, &c. Also curious mineral substances, such as particles of metallic ores, gems, &c., are frequently found embedded in those deposits of loose materials:—let him carefully collect, label, .and preserve such objects.' With regard to loose blocks, specimens should in general be detached from such only as, from the situation in which they are found, and from other circumstances, have evidently not formed part of neighbouring masses, and which are. therefore called erratic blocks. Masses of . cliffs and rocks precipitated from above at recent periods, may, however, often supply the collector with good specimens of strata not easily accessible to him.

Materials for roads thrown out in heaps, may furnish specimens for collections ; but the places from whence they are obtained should be previously ascertained. Road ■stones are frequently brought from very distant quarries.

2. Upon the whole, rock specimens should be taken fresh from the masses in their native places, Among localities most favourable for this purpose, the following may be specified : —cliffs on the sea shore—they frequently afford very perfect section® r>f the masses and strata of rocks p—precipitous sides of rivers, and their beds, and of mountain streams, which often lay open strata and beds at depths otherwise difficult to discover ; —ravines and deep valleys transversely crossing the strata, and the naked sides of which, especially, when long operated Upon by rivers and mountain-torrents, often present instructive profiles of stratification ; — artificial sections of ground, such as are produced by quarries, gravel-pits, and excavations of every description, for roads, canals, tunnels, wells, &c.

3. Where mines are worked, the collector will generally find some well informed person •or other to assist him in his pursuits; but he should use circumspection in making purchases of specimens from the common miners. ■ 4. Not unfrequently one and the same mass of rock exhibits great diversity of aspect, through the variation which takes place ■tn the mixture and proportion of its component ingredients, their colour, &c. Also the texture, such as the crystalline-granular, the slaty, the compact, &c., are subject to variation, and gradual changes have often taken place through atmospheric influence, sometimes to a considerable depth into the mass. Accidental admixtures not essential to the rock, are likewise frequently observable. As in such cases a few specimens would convey but an imperfect idea of the true character of the stratum, or other mass of rocks, suites of specimens should be formed, illustrative of most of the varieties which it affords.

5. The thickness of each stratum, and other circumstances connected with them, such as their horizontally or inclination, and the angle under which, and. toward what part of the compass, they incline, should be regularly noted.—Slight sketches of the stratification of a coast or cliff, marked with numbers corresponding to those on the labels of the specimens obtained from those strata, will be found greatly to abbreviate the trouble of writing descriptions on the spot. Examine all places where coal-pits are sunk through different strata ; procure specimens from these, and likewise of the different varieties of coal, pacing particular attention •to specimens of vegetable impressions which they, or any of the accompanying rocks, such as sandstone, &c., may afford. 7. No opportunity should be neglected to procure secondaiy fossils of every description, accompanied by specimens of the masses in which they are imbedded, and which are not seldom chiefly characterized by them. Interest should, therefore, everywhere be made with quarry men, and persons engaged in all sorts of works of excavation, to preserve whatever may be found by them in the way of petrifactions, especially osseous remains; and those persons should be particularly cautioned against breaking to pieces whole skeletons, or large portions of them. If possible, the collector should in person superintend the excavation. The following suggestions taken from Mr. De la Beche’s excellent treatise, “ How to observe in Geology,” particularly apply to osseous remains of an extremely delicate structure. Instead of endeavouring to extract these on the spot, the observer should detach so much of the rock as shall, to the best of his judgment, envelope the organic remain in a protecting case, valuable for the purpose of transport. Organic remains are generally in better condition, according to the little that is done to them prior to their final deposit in the Museum. If a fossil proves brittle to such a degree that the vibrations produced by blows to its matrix causes it to splinter up, the splinters, if sufficiently large, may be readjusted ; but it is most advisable, on seeing a fossil begin to splinter, to take some stiff clay if such can be procured, and press it down upon it. Wax or similar materials might advantageously be employed for this purpose, with small specimens. With regard to objects of great rarity and importance, and which rest exposed in a very friable rock, it may even be desirable to prepare plaster of Paris on the spot, and cover the fossil (such as the skeleton of a Saurian, &c.) with a thick coating of it. By this process the exposed part of a skeleton is set as it were in a block of plaster, from which, after carefully .working beneath it and the fossil in the friable rock, it may afterwards be freed, or in which it may be allowed to remain, as may be desired. When the scattered yet well preserved fossil bones of animals are found, it often happens that a large portion of the entire skeleton may be eventually obtained by diligent search. The accidental discovery of a small portion of bone rising through the ■rock may lead to that of entire skeletons, if sufficient care be employed. In many slaty rocks, fishes, plants, and other organic remains abundantly occur among the laminae, pressed down to so thin a a substance as not readily to be seen in a cross fracture of the rock. When, therefore such organic remains are suspected to exist in a schistose rocx, detached portions of it should be struck so as to lay open the stones in the direction of the laminae. In this way multitudes of fossil plants may be obtained, of which there were few traces in the cross fracture of the rock.

8. Wherever deposits of secondary fossils are observed, it is of importance to note any striking circumstances relative to their mode of occurring ; the proportion, for instance, in which the several species are distributed ; — whether they are more abundant in one bed of the rock than in another ; whether they are dispersed in a confused mass, or arranged parallel to the general, stratification, or confined to the surface of any particular stratum ; —or, with regard to their individual position, whether shells, for instance, are all exhibiting nearly the same view ; or if fish 6S affect a general uniform position or parallelism of their sides to the stratification; and such other peculiarities as cannot generally be exemplified even by whole suites of specimens. 9. Uncommonly interesting are the osseous remains of cavernsand grottos which frequently occur in lime-stone rocks ; these should be diligently sought after and visited, even where report may represent them as not being ossifc.vuo. uoheciuF in uis examination should proceed systematically by cutting through the layers of the incrustation which ne may nna at the oottom of them, and which are formed by the dripping down of water impregnated with calcareous particles ;— let him form a series of specimens from the layers of this stalagmitic deposit, as likewise of

the alluvial matter beneath it, of the gravel, sand, and mud, which usually envelop the osseous remains. Of these latter be should form a complete series, not only as regards the natural difference he may observe in the several bones, but likewise the accidental changes observable in them, such as appearance of being gnawed, fractured, &c. Also other objects which may be found near to, or accompanying, the bones, such as rounded concretions, fragments of stones different from the rock of the cave, should be collected, and their manner of occurring noted on the labels. In the same manner, the collector should not neglect recording every circumstance which the specimens alone are not calculated to illustrate, such as the distribution of the various bones in the caverns, their relative abundance, &c. He should also make memoranda relative to the nature and situation of the cavern itself, its direction, its dimensions, the presence or absence of water in it; —or whether it be furnished with fissures, particularly vertical ones, and if so, whether these be partly open, or filled with bones and rubble cemented together; whether parts of the sides near the opening exhibit a polish, as if produced by rubbing against;— together with other appearances which are likely to strike an attentive observer. If fissures in lime-stone rocks should, on examination, prove to be filled with osseous remains cemented together by calcareous and other matter, it will be desirable, for the purpose of ascertaining whether bones of different animals are found at different depths, to extract them from the lower as well as the higher portions of the fissure, and carefully to note the succession of the several specimens thus obtained.

10. Where petrifying sources, as they are called, occur, or waters impregnated with calcareous and other matter thrown down and consolidated into masses enveloping branches and other parts of vegetables, &c., the collector should, together with specimens, obtain any information within his reach, relative to the condition under which such deposits have been, or continue to be formed. In general, it is also desirable chemically to examine such, and other waters remarkable for any striking peculiarity. They mayreadilv be transmitted in clean strong bottles tightly closed, sealed, and labelled.

11. In tracts of country where volcanos are in action, especially if still unexplored by geologists, not specimens only should be collected, but likewise all the historical data that can be obtained relative to the different eruptions and other phenomena connected with them ; and all such circumstances should be noted as in any manner relate to the nature and appearance of those volcanos—their situation, form, craters, &c.; together with every particular concerning the lava currents, their heat before consolidation, their direction, &c.; and perfect suites should be formed of the various volcanic ejections. In endeavouring to detach specimens from a current of lava, the collector should not confine himself to the upper crust of scoria, but likewise obtain fragments from the middle and lower beds. Ashes and other pulverulent volcanic matter, are best preserved in strong bottles. Where they are found to inclose organic or other objects, these should be particularly attended to.

12. With regard to certain other rocks, to which the term tiappean is applied, and which are now likewise generally considered as igneous, or as having been propelled when in a state ol fusion, through various rocks which they overlie, the collector, under the supposition that he is not altogether unacquainted with some of those rocks, such as basalt and porphyry, is desired to direct bis attention to an alteration that may be observable in the condition of the strata in immediate contact with them. These conditions relate to change of colour, lustre, texture, partial fusion or vitrification, &c., and many of them may be illustrated by suites of specimens carefully and judiciously selected. 13. An enumeration of the several instruments required by the geological traveller, for determining the direction and inclination of the strata, for measuring heights, &c., as likewise those for mineralogical investigation would be superfluous to the proficient in geology and mineralogy, and, of no avail to the less scientific collector, who, if he wish for information, is necessarily referred to treatises on t„ose sciences. It is, however, otherwise as regards that indispensible implement, the hammer. Two of these, at least, are required; one weighing from two to four pounds and a half, for breaking tbe masses ; th f othe n dimensions, for triminiug auu lasnioning the specimens. Common hammers are not fit for the purpose’; they should be well tempered steel, and the handles of very tough wood, and most firmly inserted in the heads. y

A few masons’ tools or chisels, and a small miners pick, may likewise be occasionally tounu useful. A glove of thick leather for

the left hand, on which the trimmed, and for their convev.n B| »r e f» r P’'Y oe - Pi«e. of for labels, and paste or thick affix the specimens, constitute. V e ? ,er to woo! and cotton for delate fossils, minerals, &c., all the an On S is needful to those who undertake Ik??* collecting.

14. No particular rules can be y the operation of breaking, trimming sbioning rock specimens; but th management of the hammer, though* lienee and practice be required, iah.? 8 of difficult acquisition. Specimens intended for public . generally speaking, should be of dimensions ; some masses, es~eci ’’ pound rocks, such as conglomerate! cannot, in all their characteristic Dart. 7 studied from diminutive fragments * a ‘ ’ venient size is four to four and a b.lfh three inches, and three quarters of an - U one inch in thickness. Regularity of j - considerably facilitates the proper and r packing of the specimens. Trim shion them on the spot, where thereiiiA dance of materials ; the last blow ’ hammer will sometimes spoil a aped* All the surfaces must exhibit afrishfrafe, except where it is desirable to illustrate? tegration through atmospheric and otberk. fluences; in which case more than one!», cimen should be obtained,

15. Each object should have its onmU affixed by means of thick gum water or nZ and be accompanied by a ticket on whicTihe exact locality is given, together with suchi t . formation as the specimen alone is not calcj. lated to convey the nature of the nim from which it is taken—whether in distinct concretions, columnar, &c.; or, if stratified, the thickness of the stratum, its inclinatioa to the horizon, &c. The numbers on the specimens may, at the same time, correspond to those of the notes of his road book, if such be kept by the collector. 16. Great care should be bestowed on th proper packing of the objects. Each. spec, men is to be wrapped up in two papers;* th inner soft and less substantial than the outer, Put at tbe bottom of the packing casealajs ol hay, chaff, mess, or other soft substance perfectly dry. Place on it the' specimen! edgewise and in close contact with eid other, so that nothing can displace thea Fill up the interstices with moss or tow, ui place the other specimens in tbe same manner, layer upon layer, until the box is nearly full, when the remaining vacuities are closely filled up with the same moss, &c., before th: lid is fastene I. The use of sawdust for thii purpose is not to be recommended. Loots fragile shells and other small delicate object! are best packed by putting them, enveloped in cotton, in rows, and rolling these up a sheets of stiff paper. 17- Still greater care is to be bestowed« such mineralogical specimens as present dell' cate crystallizations. These, after beinj wrapped up loosely in silk paper, should h put separately into a chip box each, aud th empty space filled up with cotton. The chip boxes are to be placed at the bottom of th packing case. Minerals not soft or brink may be wrapped up and packed nearly in th same manner as geological specimens. Tb? are to be placed upright in rows one abon the other ; and with iheif principal surf® 6 ® parallel to two opposite sides of the packing case. The weight of such case for land cat* riage or shipping should not exceed one ho® dred weight. • 18. As the geological collector cannot I* expected to discover in his excursions nu>! specimens of simple minerals desirable to. placed in the national collection, be wi“ well, if he fall in with persons a^ u ’ in with, and in the habit of procuring ,ucb ' secure their services,, with a view to® all mineral substances that are peculiar any particular colony or tract of counKfr else claim attention on the score of their perior beauty and perfection of crysta, This latter character should be P Brl ’ c 0 attended to; it is, however, to be °“ se ?e[ , that minerals not presenting its theless prove highly interesting in spects, and that a remarkable locm**; may often lend importance to a miner® is abundantly met with at home.