James Geikie

“ Even if we reduce this estimate one half, the stoppage of the Gulf Stream would still deprive the Atlantic of a quantity of heat equal to one fourth of all that is received directly from the sun by that area.
It is beyond doubt, therefore, that the passage of so great a body of heated water into the North Atlantic, over the surface of which it spreads for so many thousands of square miles, must have a most powerful influence on the climate of those regions to which its heat is brought by prevalent winds. ”

“ Let me remark, in passing, that perhaps no accomplishment will be found so useful by the field-geologist as a power of rapid and effective sketching from Nature. If he has this power in any degree, he ought sedulously to cultivate it. ”

“ The hammer, therefore, is required to detach this outer deceptive crust. If heavy enough to do this it is sufficient for your purpose; any additional weight is unnecessary and burdensome. A hammer, of which the head weighs one pound or a few ounces more is quite massive enough for all the ordinary requirements of the field-geologist. When he proceeds to collect specimens he needs a hammer of two or three pounds, or even more, in weight, and a small, light chipping-hammer to trim the specimens and reduce them in bulk without running a too frequent risk of shattering them to pieces. ”

“ If at any time the geologist has occasion to lighten his equipment for some long mountain-expedition, where every additional ounce of weight begins to tell by the end of the day, and where, therefore, for the sake of doing as much and holding out as long as possible, he should carry nothing that is not absolutely needful for his purpose, he may advantageously combine the pocket-compass and clinometer in the one instrument to which I have already alluded. ”

“ Had he advanced inland until he reached those rocky heights he would have found the icy plain sweeping away in all directions, and bounded only by the horizon; and had he continued his journey toward the east, across what is now the German Ocean, he would have encountered nothing to break the monotonous level until he approached a low line of snow covered hills and mounds, marking the site of the ice-drowned Scandinavian Peninsula. ”

“ Our own shores would be frost-bound for a large part of the year, and perennial snow and glaciers would appear in our mountain districts. On the other hand, if we could suppose the body of warm water now flowing into the North Atlantic to be largely increased in volume, there can be just as little doubt that the climate of Northwestern Europe would be much improved, and even Spitzbergen and Nova Zembla might be rendered fit abodes for civilized communities. ”

“ As the next period of high eccentricity will not occur for many thousands of years, we need have no apprehension that we shall be deprived of the genial influence of our friendly Gulf Stream in the immediate future. ”

“ With us the prevalent winds are westerly and southwesterly, and these, as they sweep across the Atlantic, filch warmth and moisture from the Gulf Stream, which they part with as they pass over us in their course toward the northeast. How very materially our climate is thus affected will be readily seen if we compare the mean winter and summer temperatures of places in the same latitudes of North America and Europe. ”

“ In the event of that stream being diverted out of the North Atlantic, the polar currents flowing south would of course occupy the greater portion of the oceanic surface to the west of us, and hence our west and southwest winds would be cold and ungenial. Were such a catastrophe to happen, we may be sure that the Scandinavian Peninsula and a large part of our own islands would not be habitable by civilised man, while Iceland would become as inaccessible as Franz-Josef Land is now. ”

“ The blowpipe-box should contain a common blowpipe, platinum-tipped forceps, platinum wire, small bottles with the ordinary reagents, and as many of the most useful parts of blowpipe apparatus as the space will admit, consistently with the whole box being easily packed into a portmanteau. By means of the blowpipe, it is often possible to determine the nature of a doubtful rock or mineral, and to ascertain the proportion of metal in an ore. A young geologist should take with him to the field only the most essential apparatus and reagents ”

“ This leads me to remark, also, that he necessarily adopts a system of signs and contractions on his map, not only to save writing, but to prevent the map from being so overcrowded with notes as to become hopelessly confused. Every field-geologist insensibly adopts contractions of his own. ”

“ Considerable practice may be required, and many preparations may be spoiled, before the observer becomes proficient. But the labor is well bestowed, for in no other way can he obtain the same insight into the internal texture and arrangement of the rocks with which he is dealing. He sees what are the component minerals of a rock, and how they are built up to form the mass in which they occur. He likewise can detect many of the changes which these minerals have undergone, and he thus obtains a clew to some of the metamorphic processes by which the rocks of the earth's crust have been altered. ”

“ Those remarkable colonies of southern species are living evidence of the last epoch of extremely genial conditions experienced in Northwestern Europe—an epoch during which great forest growths overspread wide regions in the north—covering the British Islands, the Inner and Outer Hebrides, the Orkney and Shetland Islands, all Norway up to the extreme north, and most extensive areas which to-day lie submerged in the sea. ”

“ Some geologists prefer to carry the belt across the shoulders outside, and the hammer suspended at the back. Others provide themselves with strong canvas coat-pockets and carry the hammer there.
Even the most sharp-sighted observer is the better for the aid supplied to him by a good magnifying-glass. For field-work a pocket lens with two powers is usually sufficient. One glass should have a large field for showing the general texture of a rock, its component grains or crystals, and the manner of their arrangement ”

“ A hammer shaped as I recommend serves at times for other than purely geological purposes. On steep, grassy slopes, where the footing is precarious, and where there is no available hold for the hand, the wedge-like end of the hammer may be driven firmly into the turf, and the geologist may thereby let himself securely down or pull himself up. ”

“ The great work of the famous French engineer will have as much effect upon the Gulf Stream and the climate of North western Europe as the emptying of a teapotful of boiling water into the Arctic Ocean would have in raising the annual temperature in Greenland.—British Trade Journal. ”

“ You observe, therefore, that a fully-equipped field-geologist need not betray his occupation by any visible implement. The want of such tokens of his craft often greatly perplexes rustic observers, to whom his movements are a fruitful source of speculation. ”

“ Where it cannot be obtained, the field-geologist may succeed in preparing his slices by chipping thin splinters from the rock and reducing them upon a grindstone or whetstone. One side of the splinter is to be made as smooth and free from scratches as possible, which can be effected by polishing on a water-of-Ayr stone. This polished side is then cemented with Canada balsam to a piece of plate-glass. When quite firm, the upper side of the stone is ground down until the requisite degree of transparency is obtained. ”

“ The clinometer, or dip-measurer, is employed to find the angle at which strata are placed to the horizon—an important observation in the investigation of the geological structure of a country, and one having frequently a special economic value—as, for instance, when it points out the depth to which a well or mine must be sunk. ”

“ It is sometimes of service, when working in a district where microscopic rock-sections are required, to carry a small collection of microscopic slices of selected or typical rocks or minerals for purposes of comparison. ”

“ From the nature of his work, he has frequently occasion to make rough sections, or diagrams, and, if possessed of the power of sketching, he has abundant opportunity of aiding the progress of his researches by jotting down the outlines of some cliff, mountain, or landscape. ”

“ But he may subject his specimens to analysis in two cases, and obtain valuable, and perhaps sufficient, information as to their characters. He can easily fit up for himself a small and portable blowpipe-box, a machine for slicing and preparing rocks, minerals, and fossils, for examination under the microscope, and a microscope. ”