This book is mainly about accelerated soil erosion, which is the rapid loss of soil from slopes at rates much faster than those occurring under natural geological conditions. By soil one has in mind the whole system of weathered material and not simply the upper few centimetres in which plants grow. With this definition, it is sometimes difficult and even impossible to differentiate soil from unconsolidated bedrock materials. This broader definition of soil is matched by a broader definition of the erosion problem to include the entire area of small catchments up to several kilometres in length. This is because it is meaningful, in the environments investigated and at the scale studied, to include channel effects as significant contributors to the erosion problem. The economic and social aspects of soil erosion are two-sided; what is lost from fields and orchards is subsequently redeposited in channels and reservoirs and on fields and factories. <...>

A oportunidade de realizar esta tradujo surgiu através de contato de Alfred Kroner com Umberto Giuseppe Cordani para avaliar o interesse em publicar este manual no Brasil. Cordani considerou-o urna contribuÍ9áo significativa para a comunidade geológica nacional e solicitou a mim e a Wilson Teixeira que nos encarregássemos da tradu9áo.

L'étude des faunes paléontologiques du sud-est de l'Espagne, et spécialement de la région comprise entre Valence et Carthagène n'a été, pour le Crétacé, l'objet d'aucun travail d'ensemble ; et cependant, cette contrée en raison même de sa situation géographique, se désigne naturellement à l'attention des géologues et des paléontologistes. L'étude des fossiles que l'on y rencontre conduit, en effet, à relier les faunes paléontologiques de la France méridionale et de l'Algérie, de l'Andalousie et des Iles Baléares.

On the occasion of the III Colloquium on the Cretaceous of Spain, which took place in More-lla on the 6th, 7th and 8th September 1991 sponsored by the Spanish Group of Mesozoic, there were two field trips to illústrate the present knowledge of the Lower Cretaceous of Northeastern Iberia. These excursions are the object of the present guide-book. In the period passed between when this guide-book was written and its final publication, new results were published which represent a significant increase in our previous knowledge. These publications in international journals, which are referenced at the end of the foreword, together with the figure captions of this guide-book, which have been translated in English, will help the English reader to obtain the information necessary to understand the Lower Cretaceous of Northeastern Iberia.