THE LONDON AND HAMPSHIRE BASINS lie in depressions in the chalk occupied by various Tertiary formations, the most important of which are the London Clay and the Bagshot Sands. The latter are dry and pebbly, and are chiefly covered with heath ; while the former constitutes a stiff clay, which, although difficult to work, is of considerable fertility. Much of it is now in grass, though, when the price of wheat was higher than at present, that cereal was extensively grown. But the economic importance of the London Basin lies in the great city of London. Situated near the head of the estuary of the Thames, which offers an easy means of access into the country, and at a convenient crossing point of that river, whence good routes diverge to all parts of the British Isles, London also lies opposite the mouths of several large rivers, which drain some of the most productive regions of the Continent. To these conditions are due its rise and early importance, but its later development is the result of that change in geographical values which led to the colonial and imperial pre-eminence of the United Kingdom. It was then that London became not only a
great port, but the international market and financial centre for the most important part of the economic world. With the pro gress of other nations it has lost some of its earlier advantages ; many of its markets have moved away from it ; its port is affected by the competition of rivals both at home and abroad ; its manu factures are carried on with increasing difficulty. Nevertheless it remains the greatest port of the Kingdom, the centre of its entrepOt trade, the point upon which all its most important railways converge, and the seat of an extensive and varied industrial activity. Southampton, in the Hampshire Basin, trades mainly with the Atlantic ports of Europe, with Africa and the East, and with South America.