There are signs that this coastal strip was until a geologically recent period below sea-level; and that the coast-line is still receding is evidenced by the history of the town of Muza, once a flourishing port, now 20 m.
The latter, to which parallels in geologically similar regions in America are not unknown, is the most probable natural explanation that can be offered.
But though geologically the one set of mountains must be separated from the other, geographically it is convenient to include within the Southern Uplands the whole area between the Central Plain and the Border.
The Carpathians do not form an uninterrupted chain of mountains, but consist of several orographically and geologically distinctive groups; in fact they present as great a structural variety as the Alps; but as regards magnificence of scenery they cannot compare with the Alps.
The middle belt merges into the coastal belt, covered by geologically recent marine deposits, reaching an extreme height of 700 to 800 ft., and extending inland some 60 to 80 m.
The relation of the Americas to each other and to the rest of the world, as the home of plants and animals, is greatly affected by the breadth of the adjacent oceans, and also by the geologically recent changes of altitude whereby the breadth of the narrower parts of the lands and the oceans has been significantly altered.
Nevertheless, under some of these flows remains of plants and insects of species now living in the islands have been found - a proof that the formation as well as the denudation of the country is, geologically speaking, recent.
A more reasonable explanation ascribes the lake basin to a geologically modern depression.
Of the nearest point of the archipelago, and as it belongs geologically to Sweden (from which it is distant only 22 m.) must be considered to be physically an appendage rather than an internal part of the kingdom of Denmark.
They are known as the Sierras de Chiquitos, and are geologically interesting because of their proximity to the eastern projection of the Andes.