Cave levels and palaeo shorelines in the islands of the La Spezia Gulf (Eastern Liguria). In this paper the first results are presented of a new inventory of the karst caves in the Palmaria, Tino and Tinetto islands, bordering westward the Gulf of La Spezia. These caves are modelled in the upper Triassic-lower Jurassic limestones and dolomites belonging to the Tuscan Nappe. The two existing inventories, one worked out in the 1950s and the other one twenty years later, have been revised. A data base has been created with the results of a recent survey. Morphometric parameters of the caves (elevation, maximum and minimum width and height and total length) and the elevation of their entrance have been measured. Data have been organized in a specially designed worksheet (one for each cave), containing, in addition to the morphometric parameters, a description of the caves morphology and of the different kinds of deposits filling them. Each spreadsheet includes also a map and one or more sections of the cave, obtained updating the old inventories’ maps. The total number of inventoried caves is 21: some of those present in the old inventories have meanwhile been destroyed by quarrying activities and a submerged cave never described before has been added. Most of the caves are above sea level, five are partly flooded by the sea and only two are totally submerged. From a morphometric point of view they have been grouped in two families: one includes those caves that are developed mostly in horizontal and the other those that are equally developed in each dimension. Elevation data cluster suggesting the existence of four cave levels, at -5, +3,+12 and +32 m a.s.l., that are consistent with the height at which past sea-level markers are reported for eastern Liguria; in this area, therefore, cave levels could be considered due to different Quaternary sea-levels. The new inventory of the karst caves of the Gulf of La Spezia Islands should be regarded as well as a basic tool for their exploitation from a geo-touristic point of view: they should be considered, in fact, part of the natural heritage of the Natural Regional Park of Porto Venere.
Rapporti fra livelli di carsificazione e paleo-linee di riva nelle isole del Golfo della Spezia (Liguria orientale)
PAPPALARDO, MARTA;
2008-01-01
Abstract
Cave levels and palaeo shorelines in the islands of the La Spezia Gulf (Eastern Liguria). In this paper the first results are presented of a new inventory of the karst caves in the Palmaria, Tino and Tinetto islands, bordering westward the Gulf of La Spezia. These caves are modelled in the upper Triassic-lower Jurassic limestones and dolomites belonging to the Tuscan Nappe. The two existing inventories, one worked out in the 1950s and the other one twenty years later, have been revised. A data base has been created with the results of a recent survey. Morphometric parameters of the caves (elevation, maximum and minimum width and height and total length) and the elevation of their entrance have been measured. Data have been organized in a specially designed worksheet (one for each cave), containing, in addition to the morphometric parameters, a description of the caves morphology and of the different kinds of deposits filling them. Each spreadsheet includes also a map and one or more sections of the cave, obtained updating the old inventories’ maps. The total number of inventoried caves is 21: some of those present in the old inventories have meanwhile been destroyed by quarrying activities and a submerged cave never described before has been added. Most of the caves are above sea level, five are partly flooded by the sea and only two are totally submerged. From a morphometric point of view they have been grouped in two families: one includes those caves that are developed mostly in horizontal and the other those that are equally developed in each dimension. Elevation data cluster suggesting the existence of four cave levels, at -5, +3,+12 and +32 m a.s.l., that are consistent with the height at which past sea-level markers are reported for eastern Liguria; in this area, therefore, cave levels could be considered due to different Quaternary sea-levels. The new inventory of the karst caves of the Gulf of La Spezia Islands should be regarded as well as a basic tool for their exploitation from a geo-touristic point of view: they should be considered, in fact, part of the natural heritage of the Natural Regional Park of Porto Venere.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
