Gravel pit

“ Joe Williams hasn't waked up to the fact that there's a railroad coming through about three miles below his farm that will require thousands of yards of sand and gravel for concrete bridges, and that this is the only sand and gravel pit within a reasonable haul that's worth while. Why, do you know, Al, for years and years they've been letting people drive in here and haul away sand and gravel free of charge. ”

“ For our gravel-pit, if it be, will possibly yield us another, and a more curious object. You most of you have seen, I dare say, large stones, several feet long, taken out of these pits. In the gravels and sands at Pirbright they are so plentiful that they are quarried for building-stone. And good building-stone they make; being exceedingly hard, so that no weather will wear them away. ”

“ The best gravel for road-building stands perpendicular in the bank; that is, when the pit has been opened up the remainder stands compact and firm and cannot be dislodged except by use of the pick, and when it gives way falls in great chunks or solid masses. Such material usually contains tough angular gravel with just enough cementing properties to enable it to readily pack and consolidate, and requires no further treatment than to place it properly on the prepared roadbed. ”

“ They called Anthea 'Panther', which seems silly when you read it, but when you say it it sounds a little like her name.
The gravel-pit is very large and wide, with grass growing round the edges at the top, and dry stringy wildflowers, purple and yellow. It is like a giant's wash-hand basin. And there are mounds of gravel, and holes in the sides of the basin where gravel has been taken out, and high up in the steep sides there are the little holes that are the little front doors of the little sand-martins' little houses. ”

“ Such localities compare with the surrounding drift much as the bottom of a gravel-pit which has been partially worked compares with its banks. Look into any gravel-pit, a portion of which has already been carted away. At its bottom a number of larger stones and boulders are usually lying, too heavy for the cart, and therefore left upon the spot. Fragments of the same size and character, and equally numerous, will be seen protruding at various heights from the sides, where they are imbedded in the general mass of the drift. ”

“ As soon as the work progresses a little farther, and the finer materials are removed, these boulders will also drop out, and lie as thickly scattered over the surface of the ground, as they now do in that portion of the bottom where the pit has been completely opened and the gravel removed. ”

“ They are of the usual forms, both pointed and oval, symmetrical and well made, though rarely exceeding 41/2 inches in length. Many of them have been found on the surface of the ground; but in a gravel-pit on the water-shed between the Darent and the Medway, at an elevation of 500 feet above the sea, Mr. Bell has succeeded in obtaining several implements out of the solid bed of gravel, at depths of from 3 to 7 feet from the surface. The gravel is about 8 feet in thickness and covers a considerable area. ”

“ There clay and dirt may be washed out and the sand and gravel is sized by screens. Conveyor belts carry sand and gravel to the various processing operations and to storage bins or piles on the ground.
A “wet pit” operation produces sand and gravel from an artificial pond or lake. In some operations the sand and gravel is mined by a dredge that floats on the water (fig. 19) . In some pits, a stream of water is directed from the dredge against the bank of gravel to wash the gravel into the lake. ”

“ Gravel. —This, if of a flinty character, and not too much mixed with earthy matter, makes good roads for light traffic, if carefully watched or well rolled during formation. Pit gravel should always be screened through wire screens of 11⁄2 to 13⁄4 gauge, and the small can be used for footpaths.
In some places it is difficult to obtain any natural stone for the purposes of road metal; in these cases slag from blast furnaces or ordinary clinkers from furnaces are sometimes used. ”

“ I have seen motions of the air so furious that they have carried, mixed up in their course, the largest trees of the forest and whole roofs of great palaces, and I have seen the same fury bore a hole with a whirling movement digging out a gravel pit, and carrying gravel, sand and water more than half a mile through the air. ”

“ Judging from the section given by Sir Joseph Prestwich, [36] the highest point which the gravel attains is about 59 feet above the river, and its surface in the pit, where the implements are found, is 40 feet above it. The gravel rests upon the Cornbrash, or upper member of the Lower Oolite; but the valley itself, though partly in the limestone rock, has been cut through a considerable thickness of Oxford Clay and of Boulder Clay, which here overlies it. The gravel consists of subangular stones in an ochreous matrix, interspersed with irregular seams of sand and clay. ”

“ The right hand branch runs north-west, and the left hand branch runs south-west. Taking the south-west branch first, after travelling about 10 yards the visitor comes to "The Gravel Pits," which he reaches by ascending a mound with 13 steps. There are two pits of gravel. One of them is about 12 feet deep and the other about 15 feet. In the rocks overhead are bones distinctly visible, owing to the earthy matter having fallen away from them. Some of these bones are large. There are shelving rocks about six feet from the floor. ”

“ The production of sand and gravel from its deposits may be a relatively simple operation or one of considerable complexity. Gravel for surfacing a road may be dug from a conveniently located pit and loaded mechanically into trucks that haul it to the road. A large sand- and gravel-producing operation, however, may include not only mechanical equipment to load and transport the material but also a processing plant where it can be washed if necessary and screened to various sizes. ”

“ In sand and loose gravel which easily falls down to the machine heights up to 60 ft. are common, and sidehill cuts in loose gravel up to 300 ft. in height have been taken. In such cases, and also in the removal of landslides, great care must be taken to avoid an avalanche of the material burying the machine when the toe of the slope is cut away. The pit track should always be kept close up to the sections of track under the steam shovel, so that it can be quickly withdrawn when necessary. ”

“ In some places deep excavations were made before gravel could be obtained to form the surface of the road; and from the swampy nature of the ground much draining was required to render the foundation solid and the line durable. The danger of sinking in boggy ground for gravel was often felt. Once in particular when the party had dug to the depth of fourteen feet in a broken morass, the sergeant (Read) observed the whole mass of moss in motion. Instantly he ordered the workmen to leave the pit.pit. ”

“ Many of these beds occur at a high level; and, as they usually cap flat-topped hills, they are known as Plateau Gravels. Perhaps the most remarkable is the immense sheet of gravel which covers the flat top of St. George's Down between Arreton and Newport. Gravel pits show upwards of 30 feet of gravel, consisting of flints with some chert and ironstone, and the greatest thickness is probably considerably more than this. ”

“ In harder or more tenacious materials from two to six extra men are required, depending upon the kind of material to be excavated, and also upon good management of the contractor or foreman in charge. Wet sand and fairly loose gravel requires only two extra men, whose duty is to break down the overhanging ledges of these materials which cannot be reached by the dipper, and are liable to fall when the machine has advanced, burying it or blocking the pit behind it. The implement used by these men is a pole, Fig. ”

“ When pits cannot be sunk, it is desirable that in a suspectedly treacherous site the bore-holes should be at every 200 or 300 feet.
Excavating pits, using test-bars, and driving piles are some of the methods of determining the character of foundations, but care should be taken to ascertain in boring that boulders, or thin strata of hard gravel, are not mistaken for solid rock. In sand, mud, or soft clay they can be made by means of an iron pipe and the water-jet system. Experience has proved that boring with an auger is not so reliable as boring with a tube, such as is used for artesian wells. ”

“ I have known screw piles to penetrate hard and dense sand, gravel, soft sandy ground, limy gravel, loose silt, limy clay ground something like marl, stiff mud, chalk, clay, marl, and all kinds of water-deposited soil, and in almost every earth except firm rock, but it is not advisable to use them for anything much harder than fine sandy gravel, for the blades must then be strained very much and the pile and screw may be injured. ”

“ In the same manner, and on the same principle, so soon as the fine weather sets in, and the front-gardens begin to look gay, the graveller loads his cart with gravel, and shouldering his spade, crawls leisurely through the suburbs with his companion, peering into every garden; and wherever he sees that the walks are grown dingy or moss-grown, he knocks boldly at the door, and demands to be set to work in mending your ways. ”

“ The greater part of the hill is capped with gravel, in places from 8 to 10 feet thick, and of much the same character as that at Gravel Hill, but less ferruginous, and not containing so many quartzite pebbles. The beds here have not been excavated to the same extent as those near Brandon, the gravel being only dug for the repairs of the parish roads; but several well-fashioned implements have been found in them, mostly of pointed form. ”

“ But it is well known to geologists that a sheet of coarse angular gravel such as this, notwithstanding its looseness, is much less readily attacked by a small stream than is a surface of hard clay or even chalk. Thus plains of Tertiary deposits capped by gravel, under the action of rain or rivers develop into gravel-capped plateaus and hills, which fall abruptly into open flat-bottomed valleys. The denudation takes place at the edge, where the gravel rests on the Tertiary strata and numerous springs are given out ”

“ Where rock is scarce and gravel plentiful, the lower layer may be made of the heavier or coarser gravel, leaving the finer gravel for the upper layer, or boxing; but there is no doubt that the broken stone pitching makes the most efficient bottom layer. No gravel ballast should be used which is not free from clay or earthy sand. ”

“ In connection with the building and maintenance of gravel roads the most important matter to consider is that of selecting the proper material. A small proportion of argillaceous sand, clayey, or earthy matter contained in some gravel enables it to pack readily and consolidate under traffic or the road roller. Seaside and river gravel, which is composed usually of rounded, waterworn pebbles, is unfit for surfacing roads. ”

“ The Ideal Road Gravel.—The ideal road gravel is a mixture of pebbles, sand and earthy material, the pieces varying from coarse to fine in such a manner that when the gravel is compacted into a road surface the spaces [Pg 81] between the larger pebbles are filled with the finer material. The pebbles are of a variety of rock that is highly resistant to wear so that the road surface made from the gravel will have the quality of durability. The gravel possesses good cementing properties, insuring that the pieces will hold together in the road surface. ”

“ The tendency of material to spread under the roller and work toward the sides can be resisted by rolling that portion nearest the gutters first. To give the surface the required form and to secure uniform density, it is necessary at times to employ men with rakes to fill any depressions which may form.
[Pg 135] In order to maintain a gravel road in good condition, it is well to keep piles of gravel alongside at frequent intervals, so that the person who repairs the road can get the material without going too far for it. ”

“ These gravels are constantly in movement, being urged forward by the shore currents especially during storms. Large banks of gravel may be swept away in a single night, and in this way the coast is laid bare to the erosive action of the sea. Moreover, the movement of the gravel itself wears down the subjacent rocks. Hence in many places barriers have been erected to prevent the drift of the pebbles and preserve the land, while often it has been found necessary to protect the shores by masonry or cement work. ”

“ As it invariably happens that subaerial erosion acts most powerfully along an anticlinal line, the gravels in the hollows and channels would be the longest-preserved from destruction. And we find here and there on the surface of the Boulder-clay patches of this clayey gravel or loam generally capping the higher grounds, frequently many of them in a curved or straight line, showing the direction of the old channel in which they were originally formed. These so-called "Denudation gravels" are never of any great extent or thickness, nearly all having been removed by erosion. ”

“ Roads constructed over clay soils require a layer of at least six inches of gravel. The gravel must be deep enough to prevent the weight of traffic forcing the surface material into weak places in the clay beneath, and also to prevent the surface water from percolating through and softening the clay and causing the whole roadway to be torn up.
Owing to a lack of knowledge regarding construction, indifference, or carelessness in building or improving, roads made of gravel are often very much worse than they ought to be. ”