En el centenario de la publicación de “La Sierra Baya, Estudio geológico y económico” por Juan José Nágera

Abstract

The Monograph “La Sierra Baya” by Juan José Nágera, was published in 1919 by the Dirección General de Minas, Geología e Hidrología. Several aspects of the Monograph are analysed, underlying that the author recognizes among its objectives the usefulness for teaching, quarry industries and local people. The Monograph presents the first geological map of the area and describes the stratigraphic sequence, some structural and paleontological features and makes emphasis on the quality of the stone for the lime and cement industry as for the paving of streets and paths, backing its asseverations with physical and chemical data and analysis. In this contribution, only the first part of the Monograph is analysed, which refers to the “Geological Constitution” as the author calls it, and includes the basement and sedimentary cover. The stratigraphic sequence presented by Nágera appropriately modified and completed those of preceding authors and, in general, its proposals are still correct although the advancement of knowledge and the increase in geological observations have produced important advances. The presence of stromatolytic structures, which Nágera observes and describes, but does not identify as fossil structures, would be an example of such a situation.