I would here ask if he can calculate what time it may have required to hollow out the bed of the Elbe from its source to the sea; and to tell how often the marsh-lands, which he now sees cultivated, had been formed and destroyed by the river before they were cultivated in their present state; or if there is any security that they shall not again be taken away by the river, and again formed in the same place. If this is the case, that the river is constantly changing the fertile lands, which it forms by its inundation, what judgement are we to form by calculating the quantity of sediment in a certain measure of its muddy water.] Holland affords the very best example of this fact. It is a low country formed in the sea. This low land is situated in the bottom of a deep bay, or upon the coast of a shallow sea, where more materials are brought by the great rivers from the land of Germany than what the currents of the sea can carry out into the deep. Here banks of sand are gathered together by streams and tides; this sand is blown in hillocks by the wind; and those sand hills are retained by the plants which have taken root and fixed those moving sands. Behind that chain of hillocks, which line the sea shore, the waters of the rivers formed a lake, and the bottom of this lake had been gradually filled up or heightened by materials travelling in the rivers, and here finding rest. It grew up until it became a marsh; then man took possession of the soil; he has turned it to his own life; and, by artificial ramparts of his forming, preserves it in the present state, some parts above the level of the sea, others considerably below the ordinary rise of tides. M de Luc, who has given a very scientific view of this country in his Lettres Physiques et Morales, has there also furnished us with the following register of what had been found by sinking in that soil. It was at Amsterdam at the year 1605 in making a well. «Voici la désignation des matières qui furent trouvées en partant de la surface. 51 pieds, mêlés _de sable tourbeux_, de fable _des dunes pur_ et _d'argile_ ou limon. 22.---de même _sable des dunes pur_, et _d'argile_ bleuâtre. 14.---du même _sable_ pur. 87 pieds.--Ou rien encore n'indiquoit la présence de la mer. 55.---de _sable marin_, et _de limon_, mêles l'un et l'autre de _coquilles_ dans plusieurs couches. 142 pieds.--Soit la plus grande profondeur, où s'est manifestée la _présence_ de la mer. 49.---_Argille_ dure sans mélange de coquilles, soit que ce soit une couche _argilleuse continentale,_ ou les premiers dépôts des fleuves; ce qu'il est difficile de Déterminer. 191 pieds. 13.---Sable mêlé de pierres; qui est enfin sûrement le _sol_ vierge continental. 28.---Sable pur; continental encore; car j'ai remarqué partout dans la _Geest_, que c'est dans la couche supérieure, à une petite profondeur que se trouvent les pierres; au-dessous le _sable_ est pur.