Fig. 48. A Surrey heath

Fig. 48. A Surrey heathFig. 48. A Surrey heath

The uncultivated sands are sometimes not really so very different, and some of them, perhaps many of them, might be improved or reclaimed and made to grow these special crops if it were worth while. But they always require special treatment and therefore they have been left alone. In days of old our ancestors disliked them very much; "villanous, rascally heaths" Cobbett always called them. There were practically no villages and few cottages, because the land was too barren to produce enough food; the few dwellers on the heath, or the "heathen," were so ignorant and benighted that the name came to stand generally for all such people and has remained in our language long after its original meaning was lost. As there were so few inhabitants the heaths used to be great places for robbers, highwaymen, and evil-doers generally; Gad's Hill on the Watling St. between Rochester and Gravesend, Finchley Common, Hounslow Heath and others equally dreaded by travellers of the seventeenth and eighteenth centuries, were barren sandy tracts. But in our time we no longer need to dread them; we can enjoy the infinite charm of the breezy, open country with its brown vegetation, the pink blossom of the bell-shaped heath and the lilac blossom of theheather, the splashes of yellow from the ragwort or the gorse and the dark pine and larch plantations. In the spring the young shoots of bracken lend a beautiful light green colour to the scene, while in the autumn the faded growth covers it all with a rich brown. People now like to live amid such surroundings, and so these heaths, that have been untouched for so long and are part of the original primeval England as it was in the days of the Britons, are becoming dotted with red bricked and red tiled villas, and are fast losing their ancient character. The heaths are not everywhere dry; there are numerous clay basins where the sand lies wet, where peat forms (see p. 37), and where marsh plants like the bog asphodel, sundew, or cotton grass can be found. In walking over a heath you soon learn to find these wet places by the colour of the grass and the absence of heather. In some places there is a good deal of wood, especially pines, larches, and silver birches: all these are very common on the Surrey sands, willows also grow in the damp places. Fig. 48 shows a Surrey heath—Blackheath—with heather, gorse and bracken; with pine-woods in the distance and everywhere some bare patches of sand. Much of the New Forest is on the sand, as also is Bournemouth, famous for its fine pine woods. Fig. 49 is a view of such woods on Wimbledon common. But elsewhere there is no wood: the peasants burn the turf, and so you find their cottages have huge fireplaces: instead of fences round their gardens or round the plantations there are walls made of turf. Such are the Dorchester heaths so finely described by Hardy inThe Return of the Nativeand other novels. Other sands, however, are covered with grass and not with heather, and many of these have a special valuefor golf links, especially some of the dry, invigorating sands by the seaside. The famous links at St Andrews, and at Littlestone, are examples.

Fig. 49. Woodland and heather on light sandy soil, Wimbledon CommonFig. 49. Woodland and heather on light sandy soil, Wimbledon Common

In between the fertile and the barren sands come a number that are cultivated without being very good. They are much like the others, carrying a vegetation that is usually of the narrow leaved type (p. 72), and not very dense. On the road sides you see broom, heather, heath, harebells, along with gorse and bracken with milkwort nestling underneath: crested dog's tail and sheep's fescue are common grasses, while spurrey, knotwood, corn marigold, are a few of the numerous weeds in the arable fields. Gardens are easily dug, but it is best to put into them only those plants that, like the native vegetation, can withstand drought: vegetable gardens must be well manured and well limed. Fig. 50 shows some of this kind of country in Surrey, the barley field is surrounded by wood and very poor grass on the higher slopes.

Fig. 50. Poor sandy soil in Surrey, partly cultivated but mainly wood and wasteFig. 50. Poor sandy soil in Surrey, partly cultivated but mainly wood and waste

It is easy to travel in a sand country because the roads dry very quickly after rain, although they may be dusty in summer. Sometimes the lanes are sunk rather deeply in the soft sand, forming very pretty banks on either side.

Loams, as we have seen (p. 2), lie in between sands and clays: they are neither very wet nor very dry: not too heavy nor yet too light: they are very well suited to our ordinary farm crops, and they form by far the best soils for general farming; wheat, oats, barley, sheep, cattle, milk, fruit and vegetables can all be produced: indeed the farmer on a good loam is in the fortunate position of being able to produce almost anything he finds most profitable. In a loam district that does notlie too high the land is generally all taken up, even the roads are narrow and there are few commons. The hedges are straight and cut short, the farm houses and buildings are well kept, and there is a general air of prosperity all round. Good elms grow and almost any tree that is planted will succeed. Loams shade off on one side into sand; the very fertile sands already described might quite truly be called sandy loams. On the other side they shade off into clays; the heavy loams used to be splendid wheat soils, but are now, like clays, often of little value. But they form pleasant, undulating country, nicely wooded, and dotted over with thatched cottages; the fields are less wet and the roads are rather better than on the clays. When properly managed they make excellent grass land.

Chalky soils stand out quite sharply from all others: their white colour, their lime kilns now often disused, their noble beech trees, and, above all, the great variety of flowering plants enable the traveller at once to know that he is on the chalk. Many plants like chalk and these may be found in abundance, but some, such as foxgloves, heather, broom or rhododendrons cannot tolerate it at all, and so they will not grow.

Chalk, like sand, is dry, and the roads can be traversed very soon after rain. They are not very good, however; often they are only mended with flints, which occur in the chalk and are therefore easily obtainable, and the sharp fragments play sad havoc with bicycle tyres. The bye roads and lanes are often narrow, winding, and worn deep especially at the foot of the hills, so that the banks get a fair amount of moisture and carry a dense vegetation. Among the profusion of flowers you can find scabious, the bedstraws, vetches, ragwort,figwort, and many a plant rare in other places, like the wild orchids; while the cornfields are often yellow with charlock. In the hedgerows are hazels, guelder roses, maples, dogwood, all intwined with long trails of bryony and traveller's joy. In the autumn the traveller's joy produces the long, hairy tufts that have earned for it the name of old man's beard, while the guelder roses bear clusters of red berries. The great variety of flowers attracts a corresponding variety of butterflies, moths and other insects; there are also numbers of birds and rabbits—indeed a chalk country teems with life in spite of the bare look of the Downs. The roads running at the foot of the chalk Downs and connecting the villages, and farmhouses built there for the good water supply, are particularly rich in plants because they sometimes cut into the chalk and sometimes into the neighbouring clay, sand or rock. Now and then a spring bursts out and a little stream takes its rise: if you follow it you will generally find watercress cultivated somewhere.

Besides the beech trees you also find ash, sycamore, maples, and, in the church yards, some venerable yews. Usually the chalk districts were inhabited very early: they are dry and healthy, the land can be cultivated and the heights command extensive views over the country, so that approaching enemies could easily be seen. On the chalk downs and plains are found many remains of tribes that lived there in the remote ages of the past, whose very names are now lost. Strange weapons and ornaments are sometimes dug up in the camps where they lived and worked; the barrows can be seen in which they were buried, and the temples in which they worshipped; Stonehenge itself, the best known of all these, lies on the chalk.Several of the camps still keep the name the ancient Britons gave them—theMai-dun, the encampment on the hill, changed in the course of years to Maiden, as in Maiden Hill, near Dorchester, in Dorset, Maiden Bower, near Dunstable, and so on. Some of their roads are still in use to this day, the Icknield Way (the way of the Iceni, a Belgic tribe), the Pilgrim's Way of the southern counties and others.

Even the present villages go back to very ancient times, and the churches are often seven or eight hundred years old.

In places the land is too steep or too elevated to be cultivated, and so it is left as pasture for the sheep or "sheep walk"; where cultivation is possible the fields are large and without hedges, like those shown in Fig. 51; during autumn, winter and spring there are many sheep about, penned or "folded" on the arable land, eating the crops of swedes, turnips, rape, vetches or mustard grown for them, or grazing on the aftermath of sainfoin or grass and clover. So important are sheep in chalk districts that the whole scheme of farming is often based on their requirements, but corn is also a valuable crop, and, especially in dry districts, barley, so that chalk soils are often spoken of as "sheep and barley" soils. Although the pastures are very healthy there is not generally much food or "keep" for the animals during the summer because of the dryness.

Fig. 51. Open chalk cultivated country, Isle of ThanetFig. 51. Open chalk cultivated country, Isle of Thanet

The black soil of the fen districts and elsewhere is widely different from any of the preceding. It contains, as its colour shows, a large quantity of combustible material (Chap. V.), which has a great power of holding water. These fens are therefore very wet; until they were drained they were desolate wastes: you mayread in Kingsley'sHereward the Wakewhat they used to be like in old days, and even as late as 1662 Dugdale writes that here "no element is good. The air cloudy, gross and full of rotten harrs[1]; water putrid and muddy, yea, full of loathsome vermin; the earth spongy and boggy; and the fire noisome by the stink of smoking hassocks[2]." But during the Stuart period wide ditches or drains were dug, into which the water could flow and be pumped into rivers. This reclamation has been continued to the present time, and the black soils as well as the others in the Fen districts can be made very productive.

We have seen that a change in the soil produces a change in the plants that grow on it. The flora (i.e. the collection of plants) of a clay soil is quite different from that of a sandy soil, and both are different from that of a chalk or of a fen soil. In like manner draining a meadow or manuring it alters its flora: some of the plants disappear and new ones come in. Even an operation like mowing a lawn, if carried on sufficiently regularly, causes a change. In all these cases the plants favoured by the new conditions are enabled to grow rather better than those that are less favoured; thus in the regularly mown lawn the short growing grasses have an advantage over those like brome that grow taller, and so crowd them out. When land is drained those plants that like a great quantity of water no longer do quite so well as before, while those that cannot put up with much water now have a better chance. In the natural state there is a great deal of competition amongplants, and only those survive that are adapted to their surroundings. You should remember this on your rambles and when you see a plant growing wild you should think of it as one that has succeeded in the competition and try to find out why it has been enabled to do so.

[1] Harr is an old word meaning sea-fog.

[2] Hassock is the name given to coarse grass which forms part of the turf burnt in the cottages.

Apparatus required.

The apparatus in Fig. 54. The under surface, of the lips of the beakers should be vaselined to prevent the water trickling down the sides.

It is not uncommon to find cliffs or crags in inland places, but they usually show one very striking difference from seaside cliffs. The seaside cliffs may be nearly vertical, but the inland cliffs are not, excepting for a little way at the top; lower down a heap of stones and soil lies piled against the face of the cliff and makes a slope up which you can climb. If you look at the cliff you can find loose fragments of it split off either by the action of freezing water (p. 83) or by other causes ready to roll down if sufficiently disturbed. So long has this been going on that a pile has by now accumulated, and has been covered with plants growing on the soil of the heap. Our interest centres in this soil; no one has carried it there; it must have been made from the rock fragments. When you get an opportunity of studying such a heap, do so carefully; you can then see how, starting from a solid rock, soil has been formed. This breaking down of the rock is called weathering.

Fig. 52. Cliffs at the seaside, Manorbier, PembrokeshireFig. 52. Cliffs at the seaside, Manorbier, Pembrokeshire

The same change has gone on at the top of the cliff. Fragments have split off and the rock has brokendown into soil which stops where it is unless the rain can wash it away. If there are no cliffs where you live you can see the same kind of action in the banks of the lanes, in a disused quarry, gravel pit or clay pit. Wherever a vertical cutting has been made this downward rolling begins and a heap quickly forms, making the vertical cut into a slope. Plants soon begin to grow, and before long it is clear that soil has been made out of the fragments that have rolled down. This process is known as soil formation, but there is another always going on that we must now study. The heap does not invariably lie at the foot of the cliff. If there is a stream, river, or sea at the foot the fragments may be carried away as fast as they roll down: the differences shown in Figs. 52 and 53 between a cliff at the seaside and a cliff inland arise simply in this way. In inland districts great valleys are in course of time carved out, and at the seaside large areas of land have been washed away.

What becomes of the fragments thus carried away by the water? The best way of answering the question would be to explore one of these mountain streams and follow it to the sea, but we can learn a good deal by a few experiments that can be made in the classroom. We want to make a model stream and see what happens to little fragments of soil that fall into it.

Fig. 53. Inland cliff. Salisbury Crags, Arthur's Seat, EdinburghFig. 53. Inland cliff. Salisbury Crags, Arthur's Seat, Edinburgh

Fix up the apparatus shown in Fig. 54. The small beaker A is to represent the narrow mountain stream, the larger oneBstands for the wide river, and the glass jarCfor the mouth of the river or the sea. Run water through them; notice that it runs quickly throughA, slowly throughB, and still more slowly throughC: we want it to do this, because the stream flows quickly and the river slowly.

Now put some soil intoA. At once the soil is stirred up, the water becomes muddy, and the muddy liquid flows intoB. But very soon a change sets in, the liquid inAbecomes clear, and only the grit and stones are left in the bottom: all the mud—the clay and the silt—is washed intoB. There it stops for a long time, and some of it will never wash out. The liquid flowing intoCis clearer than that flowing intoB. If you keep on putting fresh portions of soil intoAyou can keepBalways muddy, althoughAis usually clear. At the end of the experiment look at the sediment in each beaker: inAit is clear and gritty, inBit is muddy. If you can get hold of some sea water put some of the liquid fromCinto it: very soon this liquid clears and a deposit falls to the bottom, the sea water thus acting like the lime water on p. 20.

Fig. 54. Model of a stream. In _A_, where the stream flows quickly, the water is clear and the sediment free from mud. In _B_, where it flows slowly, the water is turbid and the sediment muddyFig. 54. Model of a stream. InA, where the stream flows quickly, the water is clear and the sediment free from mud. InB, where it flows slowly, the water is turbid and the sediment muddy

The experiment shows us that the fine material washed away by a quickly flowing stream is partly deposited when the river becomes wider and the current slower, and a good deal more is deposited by the action of the salt water when the river flows into the sea. The rock that crumbles away inland is spread out on the bed of the river or at its mouth.

Fig. 56. The two sides of the river at the bendFig. 56. The two sides of the river at the bend

The river Stour at Wye showed all these things so clearly that I will describe it; you must then compare it with a river that you know, and see how far the same features occur. At the bridge the stream was shallow and flowed quickly: the bottom was gritty and pebbly, free from mud, and formed a safe place for paddling. Before the bridge was built there had beena ford here. But further away, either up or down, the stream was deeper and wider, flowed more slowly, had a muddy bottom, and so was not good for paddling. At one place about a mile away some one had widened out the river to form a lake, but this made the stream flow so slowly (as it was now so much wider) that the silt and clay deposited and the lake became silted up, i.e. it became so shallow that it was little more than a lake of mud. The same facts were brought out at the bend of the river. On its convex side, Fig. 55, the water has rather further to go in getting round the bend than on its concave sideB, it therefore flows more quickly, and carries away the soil of the bank and mud from the bottom. But on its concave aide where it flows more slowly it deposits material. There is at the bend a marked difference in depth at the two sides. On its convex side the stream is rapid and deep, and scours away the bank; on its concave side it is slower, shallower, and tends to become silted up. Thus the bend becomes more and more pronounced unless the bank roundAis protected (the other bank of course needs no protection) and the whole river winds about just as you see in Fig. 56, and is perpetually changing its course, carrying away material from one place, mixing it up with material washed from somewhere else, and then deposits it at a bend or in a pool where it first becomes a mud flat and then dry land. Some, however, is carried out to sea. We need not follow the Stour to the sea; reference to an atlas will show what happens to other rivers. Some of the clay and silt they carry down is deposited at their mouths, and becomes a bar, gives rise to shoals and banks, or forms a delta. The rest is carried away and deposited on the floor of the sea.Material washed away by the sea from the coast is either deposited on other parts of the coast, or is carried out and laid on the floor of the sea. Thus a thick deposit is accumulating, and if the sea were to become dry this deposit would be soil. This has actually happened in past ages. The land we live on, now dry land, has had a most wonderful history; it has more than once lain at the bottom of the sea and has been covered with a thick layer of sediment carried from other places. Then the sea became dry land and the sediment became pressed into rock, which formed new soil, but it at once began to get washed away by streams and rivers into new seas, and gave rise to new sediments on the floor of these seas. And so the rock particles have for untold ages been going this perpetual round: they become soil; they are carried away by the rivers, in time they reach the sea; they lie at the bottom of the sea while the sediment gradually piles up: then the sea becomes dry land and the sediments are pressed into rocks again. The eating away of the land by water is still going on: it is estimated that the whole of the Thames valley is being lowered at the rate of about one inch in eight hundred years. This seems very slow, but eight hundred years is only a short time in geology, the science that deals with these changes.

Fig. 56. The winding river Stour. The river winds from the right to the left of the picture, then back again, and then once more to the left, passing under the white bridge and in front of the barn.Fig. 56. The winding river Stour. The river winds from the right to the left of the picture, then back again, and then once more to the left, passing under the white bridge and in front of the barn.

Water does more than merely push the rock particles along. It dissolves some of them, and in this way helps to break up the rock. Spring water always contains dissolved matter, derived from the rocks, some of which comes out as "fur" in the kettles when the water is boiled.

Rocks are also broken up by other agents. There is nearly always some lichen living on the rock, and if youpeel it off you can see that it has eaten away some of the rock. When the lichen dies it may change into food for other plants.

We have learnt these things about soil formation. First of all the rocks break up into fragments through the splitting action of freezing water, the dissolving action of liquid water, and other causes. This process goes on till the fragments are very small like soil particles. Then plants begin to grow, and as they die and decay they give rise to the black humus that we have seen is so valuable a part of the soil (p. 51). This is how very many of our soils have been made. But the action of water does not stop at breaking the rock up into soil; it goes further and carries the particles away to the lower parts of the river bed, or to the estuary, to form a delta, and mud flats that may be reclaimed, like Romney Marsh in England and many parts of Holland have been. Many of our present soils have been formed in this way. Finally the particles may be carried right away to sea and spread out on the bottom to lie there for many ages, but they may become dry land again and once more be soil.

One thing more we learnt from the river Stour. Why did it flow quickly at the bridge and slowly elsewhere? We knew that the soil round the bridge was gravelly, whilst up and down the stream it was clayey. The river had not been able to make so wide or so deep a bed through the gravel as it had through the clay, and it could therefore be forded here. We knew also that there was a gravel pit at the next village on the river, where also there was a bridge and had been a ford, and so we were able to make a rough map like Fig. 57, showing that fords had occurred at the gravelpatches, but not at the clay places. Now it was obvious that an inn, a blacksmith's forge, and a few shops and cottages would soon spring up round the ford, especially as the gravel patch was better to live on than the clay round about, and so we readily understood why our village had been built where it was and not a mile up or down the stream. Almost any river will show the same things: on the Lea near Harpenden we found the river flowed quickly at the ford (Fig. 58), where there was a hard, stony bottom and no mud: whilst above and below the ford the bottom was muddy and the stream flowed more slowly. At the ford there is as usual a small village. The Thames furnishes other examples: below Oxford there are numerous rocky or gravelly patches where fords were possible, and where villages therefore grew up. Above Oxford, however, the possibilities of fording were fewer, because the soil is clay and there is less rock; the roads and therefore the villages grew up away from the river.

Fig 57. Sketch map showing why Godmersham and Wye arose where they did on the Stour. At _A_, the gravel patch, the river has a hard bed and can be forded. A village therefore grew up here. At _B_, the clay part, the river has a soft bed and cannot be forded. The land is wet in winter, and the banks of the stream may be washed away. It is therefore not a good site for a villageFig 57. Sketch map showing why Godmersham and Wye arose where they did on the Stour. AtA, the gravel patch, the river has a hard bed and can be forded. A village therefore grew up here. AtB, the clay part, the river has a soft bed and cannot be forded. The land is wet in winter, and the banks of the stream may be washed away. It is therefore not a good site for a village

Fig. 58. Ford and Coldharbour, near HarpendenFig. 58. Ford and Coldharbour, near Harpenden

The teacher is advised to procure, both for his own information and in order to read passages to the scholars:

Gilbert White,Natural History of Selborne.Charles Darwin,Earthworms and Vegetable Mould(Murray).A. D. Hall,The Soil(Murray).

Mr Hugh Richardson has supplied me with the following list of questions, through many of which his scholars at Bootham School, York, have worked. They are inserted here to afford hints to other teachers and to show how the lessons may be varied. They should also prove useful for revising and testing the scholars' knowledge.

1. Collect samples of the different soils in your neighbourhood—garden soil, soil from a ploughed field, from a mole-hill in a pasture field, leaf mould from a wood, etc. Collect also samples of the sub-soils, sand, gravel, clay, peat.

2. Supplement your collection by purchasing from a gardener's shop some mixed potting soil and also the separate ingredients used to form such a mixture—silver sand, leaf mould, peat.

3. How many different sorts of peat can you get samples of? Peat mould, peat moss litter, sphagnum moss, turf for burning, dry moor peat?

4. Find for what different purposes sand is in use, such as mortar making, iron founding, scouring, bird cages, and obtain samples of each kind.

Analysis of Garden Soil. About a handful of soil will be required by each pupil.

5. Describe the appearance of the soil. Is it fine or in lumps? Does it seem damp or dry? Can you see the separate particles of mineral matter? How large are these? Is there any evidence of vegetable matter in the soil?

6. Put some of the soil in an evaporating basin and over this place a dry filtering funnel. Warm the basin gently. Is any moisture given off?

7. Dry some of the soil at a temperature not greater than that of boiling water, e.g. by spreading it out on a biscuit tin lid, and laying this on a radiator. How have the appearance and properties of the soil been changed by drying?

8. Crumble some of the dried soil as finely as you can with your fingers. Then sift it through a sheet of clean wire gauze. What fraction of the soil is fine enough to go through the gauze? Describe the portion which will not pass through the gauze. Count the number of wires per linear inch in the gauze.

9. Mix some of the soil with water in a flask. Let it stand. How long does it take before the water becomes quite clear again?

10. Mix some more soil with water. Let it settle for 30 seconds only. Pour off the muddy water into a tall glass cylinder. Add more water to the remaining soil, and pour off a second portion of muddy water, adding it to the first, and so on until all the fine mud is removed from the soil. Allow this muddy water ample time to settle.

11. When the fine mud has settled pour off the bulk of the water; stir up the mud with the rest of the water; transfer it to an evaporating basin, and evaporate to dryness.

12. Does this dried mud consist of very tiny grains of sand or of some material different from sand? Can you find out with a microscope?

13. If the mud consists of real clay and not of sand it should be possible to burn it into brick. Moisten the dried mud again. Roll it if you can into a round clay marble. Leave this to dry slowly for a day. Then bake it either in a chemical laboratory furnace or in an ordinary fire.

14. Return to the soil used in Question 10, from which only the fine mud has been washed away. Pour more water on to it, shake itwell, and pour off all the suspended matter without allowing it more than 5 seconds to settle. Repeat the process. Collect and dry the poured off material as before. What is the material this time, sand or clay?

15. Wash the remaining portion of the soil in Question 14 clean from all matter which does not settle promptly. Are there any pebbles left? If so, how large are they, and of what kind of stone?

16. Take a fresh sample of the soil. Mix it with distilled water in a flask. Boil the mixture. Allow it to settle. Filter. Divide the filtrate into two portions. Evaporate both, the larger portion in an evaporating basin over wire gauze, the smaller portion in a watch glass heated by steam. Is any residue left after heating to dryness?

17. Take a fresh sample of soil. Spread it on a clean sand bath and heat strongly with a Bunsen flame. Does any portion of the soil burn? Is there any change in its appearance after heating?

18. To a fresh sample of soil add some hydrochloric acid. Is there any effervescence? If so, what conclusions do you draw?

19. Make a solution of soil in distilled water, and filter as before. Is this solution acid, alkaline or neutral? Are you quite certain of your result? Did you test the distilled water with litmus paper? And are you sure that your litmus does not contain excess of free acid or free alkali?

Peat.

20. Examine different varieties of peat collected (see Question 2) and describe the appearance of each.

21. Burn a fragment of each kind of peat on wire gauze. What do you notice?

22. Boil some peat with distilled water and filter the solution. What colour is it? Can you tell whether it is acid, neutral or alkaline? Evaporate some of the solution to dryness.

Out-of-doors.

23. Describe the appearance of the soil in the flower beds (a) during hard frost, (b) in the thaw which follows a hard frost, (c) after an April shower, (d) in drought at the end of summer, (e) in damp October weather when the leaves are beginning to fall.

24. Is the soil equally friable at different times of the year?

25. In what way do dead leaves get carried into the soil?

26. Can you find the worm holes in a garden lawn? in a garden path?

27. Take a flower bed or grass plot of small but known area (say 3 yards by 2 yards) and a watering can of known capacity (say 3 gallons). Find how much water must be added to the soil before some of the water will remain on the surface. What has been the capacity of the soil in gallons per square yard?

28. Take two thermometers. Lay one on the soil, the other with its bulb 3 inches deep in the soil. Compare their temperatures at morning, noon and night.

29. Find from the 25-inch Ordnance map the reference numbers of the fields near your school. Make a list of the fields, showing for what crop or purpose each field is being used.

Acid waters,40

Air in soil,16,70,95

Bars in estuaries,122

Black soils,36

Blowing sands,22

Bricks,10,16-18

Chalk,26,96

Chalk soils,110-112

Clay,6,9-21

Clay soils,75,100-102

Cliffs,116-119

Darwin's experiments,11,56

Deltas,122

Drainage,19,96

Dwellers in the soil,53-63

Earthworms,54-56

Error of experiment,48

Fallow,14,95

Fens,112

Flora,114

Fords,126

Frost, action of, on soil,83

Grassland,75

Grit,6

Hales's experiment,73

Heaths,104

Heavy soils,100

Hoeing,86-93

Humus,36,51,93,125

Hypotheses,36

Land slips,12

Leaf mould,33

Light soils,104

Lime, action of, on clay and soil,19-21,96-98

Lime water,19

Loams,2,65,108

Back to Index Next