In 1687, after he graduated in Medicine, young Antonio Vallisneri (1661-1730) returned in the Duchy of Modena and Reggio. In those years he mainly served as general practitioner; nevertheless, he also devoted many studies to various aspects of the natural sciences. He performed many observations, accurately reporting them in seven “Quaderni” written between 1694 and 1701.
Though the Earth sciences occupy only a small part of these diaries, the accuracy of the notes makes them a precious token of the scientifijic praxis adopted by the author in this field of study. This paper deals with the analysis of these early geological reports, pointing out the main criteria of Vallisneri’s experimental method and paying attention to the great signifijicance which these documents had in the elaboration of some of his published works.