Cliffs on the Seine not marine.

is not deformed even by disintegration and the wash of rain.

Cones are the squares into which nature throws solids to resist the rush of aqueous down-pour. Rain, agglomerated in a steep hollow is Napoleon's condensed column of attack, irresistible save to the Iron Duke.

The precipices and columns of chalk which stand out abruptly from the sloping banks of the Seine in Normandy, which Lyell considers as remnants from the surrounding denudation of the sea, exist only, because being harder than the neighbouring chalk, they have yielded more slowly to atmospheric disintegration and the wash of rain. Their comparative hardness is probably owing to the effect of the infiltration of water of petrifying power. Nature is a great chemist, and always at work. Air and water together are her great disintegraters, neither of them singly. In dry air alone perishable materials will remain unaltered for centuries, nay, thousands of years; and under water wood will retain the sharp edges of the carpenter's work for ages after the upper parts have been turned to powder under the action of the two powers. And it is astonishing to what a depth below the surface these two powers together will alter even the hardest rocks. They

decay into soft mud, earth, clay, or sand. This happens on the surface. We see it and believe it. Some of us are rather hard of belief that these soft substances should become hard again under the surface; that is, unless melted by heat or at least baked by heat like a brick. Yet the transformation of the soft into the hard without heat goes on under our eyes in nature and art daily. In art stucco, concrete, cement, plaster, and mortar, are daily formed. In nature petrifying springs turn the softest materials to the hardest in a few hours. Many springs deposit pure flint or limestone. The enormous areas over which water impregnated with iron has acted as a cement may be seen by the red and yellow colouring of strata. Place a piece of iron in sand exposed to the elements, and it forms a mass of stone. By the action of heat the purest looking water daily encrusts our kettles and cauldrons with intensely hard stone.

But though Lyell describes these rocks as having a crystalline texture like marble,' he also describes them as being, even at this moment, suffering decay and disintegration, and as exhibiting a white powdery surface,' and again as being in a state of slow decomposition, either exfoliating or being covered with powder, like the chalk cliffs on the English coast.'

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To account for the rarity of these so-called marine inland cliffs, and for their intermittent character, Lyell says, 'secondly, that precipitous rocks have often decomposed and crumbled down; and thirdly, that many terraces and small cliffs may now lay concealed beneath a talus of detrital matter.'

Here we get subaerial denudation and its effects. And this is the true history of all denudation. These taluses are of very constant occurrence, as I stated in the second edition of the Tree-lifter,' and may be shown where they do occur, because they are unstratified. what formed them but subaerial denudation? Or in plain English, the decay of the faces of the precipices, or the run of the hills,' above them, or both.

But

In general the philosophic and the unphilosophic are terribly put out by the powers here claimed for the wash of rain.' 6 Yet when the word 'flood' is used, they will allow you to wash away articles of any size or description, natural or artificial. A flood however, is simply the effect of rain, as the flood' was the same.

If only one year's rain could remain where it fell, the surface of the whole terraqueous globe would be covered a yard deep with fresh water. Is this so small a cause as to produce no effect?

CHAPTER III.

DENUNDATION OF WEALD RUNS THROUGH

WITHOUT PONDING.

RIDGES

THE WEALD ORIGINALLY COVERED WITH TERTIARY STRATA. TERTIARY STRATA ORIGINALLY UNITED THE BASINS OF LONDON, PARIS, AND HAMPSHIRE. THE WEALD VALLEY, NO VALLEY,

BUT A HILL. AND ITS DENUDATION PASSES TO TWO SEAS BY NUMEROUS DISTINCT TRUNK VALLEYS. THESE VALLEYS WERE MADE BY RAIN AND RIVERS, NOT BY THE SEA, NOR BY MATHEMATICAL EARTHQUAKES.' THE SEA IS ERODING THE COAST OF SUSSEX. YET THE RIVERS ARE FILLING THEIR ESTUARIES. THE GRADIENT OF A VALLEY IS NEVER PERMANENT IN ANY PART. HOW RIVERS RUN THROUGH RIDGES OF HILLS EVEN WITHOUT PONDING. THE WEALD VALLEY MAY BECOME THE 'OOLITIC VALLEY.' MANTELL'S 'DILUVIAL' VALLEY. THE AXIAL VALLEY OF THE ROTHER. ROMNEY MARSH THE DELTA OF THE ROTHER. EMBANKMENT OF NEW LAND STILL GOES ON. ONLY MUD GOES OUT TO SEA. THE CHALK FLINTS WHICH COVERED THE WEALD HILL. THE ITCHEN ONCE ROSE ON THE WEALD HILL. THE WATER SLOPE OF THE ARUN IS STILL ROBBING THE WATERSLOPE OF THE ITCHEN. ROMNEY AND HYTHE ONCE CINQUE PORTS. THEY NOW BEAR SHEEP NOT SHIPS.

his own

To denude the Weald, Lyell uses submarine theory, but not alone. Fiat mixtura. He adds a quantum sufficit of the mathematical earthquake system of Messrs. Martin and Hop

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kins. Later in the day, in Calabria, we shall find the dose of earthquake made up with aqua pura that is, with running water,' or the erosion theory.

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In the original elevation of the Weald district, the igneous action was strongest from east to west along the centre of the yellow Hastings sand, No. 5, where Forest Range' is marked in the map; so that it formed there what is called an anticlinal line or axis; that is, the beds or strata were raised highest along the ridge, and inclined or dipped, like a barn roof, both ways, to the north and south, while they stretched to the east and west. The conventional termline of strike' is a bad translation by sound instead of by sense, from the German streichen, and means line of stretch.

The lips of the light blue Weald clay, No. 4, originally joined over this ridge of the Hastings sand; those of the green lower greensand, No. 3, over the Weald clay; those of the darkblue gault, No. 2, over the lower greensand; and those of the light coloured chalk and upper greensand, No. 1, over the gault.

Lyell thinks that the pink tertiary strata did not join over the chalk, because they may have been deposited from his favourite marine denudation after the chalk was raised. He writes: