A Study of the Rhætic Strata of the Val di Ledro in the Southern Tyrol

Abstract

ON the western side of the Lago di Garda is situated a tract of Secondary rocks which has been comparatively little explored by geologists. Lying as it does exactly upon the Austro-Italian frontier, this area has neither been described by Stoppani and the Italian geologists, nor has it received full justice from the officers of the Vienna geolorische Reichsanstalt; and under these circumstances Prof. Zittel of Munich has pointed it out to the author of the present paper as a promising field of study. Mr. Dale's work will certainly be of considerable use to future explorers of the district, though not carried out in sufficient detail to warrant, in his own case, any very important generalisations. Indeed, the memoir consists almost wholly of transcriptions of notes and rough drawings of sections relating to a number of different localities which are indicated by reference to a key-map. The author's general conclusions, so far as they go, are shown in a very clear and useful table, from which it appears that at this point of the Alps, the Jurassic and Rhætic strata (including in the former the Tithonian) have a united thickness of from 6,000 to 7,000 feet. Vast as is the estimate, no one acquainted with this or the surrounding districts will be inclined to regard it as excessive.

A Study of the Rhætic Strata of the Val di Ledro in the Southern Tyrol.

By T. Nelson Dale, jun., Member of the Geological Society of France. Pp. 69, with Map and Sections. (Paterson, New Jersey, 1876.)