[124] The district on the right bank of the Parana, above Santa Fe and Parana, seems to be due to a recent subsidence. The river is, on the other hand, compelled to effect active erosion in crossing the high lands between Santa Fe and Buenos Aires. It is curious that the break or fall at Villa Urquiza occurs precisely above the bend of the Parana. A less marked break has been recognized further north, in the latitude of Lavalle, above the Goya bend. It seems that the diminution in the excavation of the valley is due to the erosion which the current effects laterally on the cliffs of the left bank. Above Corrientes the width of the main arm of the Parana varies, as a rule, from 2,600 to 6,500 feet. The width of the river-plain over which the floods spread is still more irregular. Between Santa Fe and Parana, where it is especially narrow, it is still ten miles wide. Lower down it gradually broadens to a width of sixty-five miles at the head of the estuary. The scenery is not the same in all sections of it. The vegetation on the islands is richer and more varied up river, and tropical essences (laurel-timbo) are found below the Bajada, forming clumps of trees covered with creepers. [Illustration: THE PARANA AT CORRIENTES. _Banks and islands partially fixed by vegetation._ Photograph by Widmayer.] [Illustration: THE _BARRANCA_ AT PARANA (ENTRE RIOS), LEFT BANK. _It is composed of clays and of beds of conchiferous terrestrial limestone, which have supplied the lime-kilns for more than a century._ Photograph by Boote. PLATE XXI. To face p. 244.]