Naturally, the soil of such a vast area as that covered by the two Republics of Argentina and Uruguay is varied to an extent with which a book like the present cannot attempt to deal adequately. The greatest feature is, however, the celebrated Pampean formation which obtains over the whole of the Province of Buenos Aires, the greater parts of the Provinces of Santa Fé, Córdoba, San Luis and Mendoza, the National Territory of the Pampa Central, the Republic of Uruguay, and extends southwards beyond the Argentine Rio Negro. In many places on this formation there are also later alluvial deposits. The lightest soils, those with the smallest proportion of clay and consequently the loosest, are found in the West, near the Andes. Starting from the most sandy western region, the soil grows more and more compact towards the east, along the River Paraná, the South of the Province of Santa Fé and most of the Republic of Uruguay, the Northern part of the Province of Buenos Aires (where rather heavy soils predominate); while in the South and South-West, that is to say the southern portion of the Province of Córdoba, the National Territory of the Pampa Central and the central and southern part of the Province of Buenos Aires, the soil is of lighter, though firmer consistency, than that of the western part. The generally salient qualities of the Pampean soil are richness in humus, deficiency in lime and good proportions of nitrogen and phosphoric acid. A characteristic feature of the subsoil is stratified layers of more or less calcareous concretions known as TOSCA (tufa or tophos stone). This layer is sometimes deep down; but in the southern region of the Province of Buenos Aires, beginning at Tandíl and Azul, it reaches nearly to the surface, so as to appear immediately under the soil, thus forming a waterproof subsoil impenetrable by roots. The present writer has seen wheat growing on less than an inch of soil above the tosca; the roots spreading out at right angles to the stalks. These layers of tosca or, in other parts, clay, are of great importance for holding water; seldom at any great distance from the surface. On low and level plains when the soil is light or loose, chains of sand-hills are formed by the prevailing winds. Some of these are kept stationary by quick-growing vegetation, while others are constantly shifting. The shifting sandhill is, however, fast disappearing in consequence of the advances of pastoral industry; for, and by, which they are becoming fixed by herbaceous growth. The tosca and clay subsoils have in many parts occasioned the formation of lagoons and swamps; the waters of which are, usually, at least brackish and often salt. A white or grey efflorescence seen in these swamps is locally called saltpetre, but in fact it only contains slight traces of nitre. Towards the extreme North of the Province of Entre Rios and the Republic of Uruguay red soil heralds one’s approach to subtropical or tropical vegetation.