CO885-(21-23) — Page 488

RECORD OFFICE

Reference:

C.O. 885

22 PUBLIC RECORD OFFICE, LONDON

ALLY WITHOUT PERMISSION OF THE BE REPRODUCED PHOTOGRAPHIC:

COPYRIGHT PHOTOGRAPH-NOT TO

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should then be removed and the greater part of the water allowed to run out. When only a little remains, the cork should be re- placed while the bottle still remains in the same inverted position. It should then be securely sealed. If necessary, a small cavity should be excavated in the rock to facilitate the operation.

If the gas is escaping from water, a bottle is immersed in the water which is allowed to fill it entirely. It is then inverted and held with the mouth, still under water, in such a position as to catch the gas as it rises. When it is full of gas it must be corked before it is removed from the water, and afterwards sealed. A large amount of gas is desirable for analysis, but it will seldom be feasible to transport more than about a gallon.

XV.

ENTRIES IN THE NOTE BOOK.

When a specimen is taken the fact should at once be entered in a notebook with the date and the distinguishing number or letter. The locality should be stated as nearly as possible, even if it be only by giving the distance or time occupied by the journey from the last definitely known point. The note should give a rough description of the specimen and the rock from which it is taken, If the latter possesses bedding or foliation, the amount and direction of the dip, or, when these cannot be determined, the direction of the strike, should be stated. The dip may he ascertained by means of any form of clinometer or level by which the angle of a slope can be measured, and for the direction of the dip or strike an ordinary compass may be used. The geologist usually employs a simple combination of a clinometer and compass. Care must be taken to get the real direction and angle as the lines of bedding in a quarry or cliff may at first sight give a quite erroneous impression. If possible, the determination should be made on the actual surface of a hed. If the country has been surveyed, the directions of the hills as shown in the map will usually give a truer idea of the strike and consequently of the real direction of the average dip than a single observation on a small exposure. If the surface of a bed he exposed, the direc tion in which a little water descends its slope will be that of the dip, and if the bed slopes down into a pool or river the line where it meets the water gives the direction of the strike. It should be made clear whether the direction of the dip or strike is given with reference to the true or the magnetic north.

Where cross bedding occurs or slaty cleavage, these should be distinguished from the real dip, and the characters they present should be described.

Where a series of beds of different composition or appearance is seen, a table should be given showing the succession and the thickness of each bed and the distinguishing numbers or letters of any specimens taken from it. The highest beds should be

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placed at the top, but the numbering will commence with the lowest bed that is visible, thus:-

Soil

31

O, P, Q. 4 Bluish grey shaly limestone 13'

M, N. 3 Dark shale

L. 2 Light sandy shale...

K. I Fissile yellow sandstone (base not seen).

6'

7 dip 30o, N., 20o E. 4/

If a sill or dyke of igneous rock be met with the thickness and inclination should be stated, and in the case of a sill it should be mentioned whether it is always found between the same two beds of sedimentary rock or not.

All the information which accompanies the specimens should be repeated in the note book, and any other details should be added with regard to the character and relations of the rocks which may appear likely to be of use or interest. Among other things details should be given of the occurrence of springs or of "swallow holes" into which water flows, and of the direction and character of the drainage, also of native workings and mining or metallurgical operations and processes and other industries in which mineral products are employed. Information or traditions with regard to the advance or retreat of the sea or lakes or variations in the course of rivers, or with regard to earthquakes or the fall of meteoric stones should also be recorded, Recent occurrences of this description should be carefully investigated, but where the inquiry is made by means of an interpreter, especially if he has received any education on European lines, care must be taken to prevent the evidence being distorted in conformity with preconceived ideas.

Notes should always be illustrated by sketches and sketch maps, and the same numbers or letters should be used on these as in the notes and on the specimens. A sketch should, as far as is practicable, be made of every exposure, as well as of hill outlines, which have always geological significance. Stress has already been laid on the importance of sketches of the larger fossils or fossil groups being made before they are disturbed. Photography should be freely used but should always be supplemented by sketches, because these can be lettered at the time.

If a map exists or is in course of construction the locality where a specimen is taken should be indicated on it by the distinguish- ing number or letter and, if necessary, the date. The direction of the dip may be shown byn short arrow and the angle may be added in figures. Sketch maps on a larger scale will often be desirable to explain the notes, and in some cases an exact survey of a small area on a large scale may be desirable. The importance of the careful survey of caves has already been insisted on.

The position of a place mentioned in the notes, but not appear- ing on an accompanying map, should be indicated by means of its latitude and longitude, or by its direction and distance from a well known locality.