Questions on Geologic Principles

The appearance of this translation of Eduard Reyer's Geologische Prinzipienfragen (1907) is as timely as John Biram's English translation of Alfred Wegener's Die Entstehung der Kontinente und Ozeane (1912, 4th rev. ed., 1928, Dover, 1966). Both translations mark a general revival of interest in the historical growth of two major geodynamic concepts: gravity tectonics and continental drift. In a way, these two aspects of geodynamics are complementary. Reyer, who lived from 1849 to 1914, drew attention to the potential energy created by vertical crustal movements; Wegener, who lived from 1880 to 1930, stressed the importance of great horizontal displacements. Wegener's book appeared to achieve a real breakthrough for continental drift, an idea that had been ripening since the seventeenth century, but most geoscientists rejected his proposals because of the preconceived opinion that crustal rocks were too strong and that the proposed driving forces too weak for such a process. An entirely new branch of geonomy paleomagnetism had to be developed before enough diagnostic facts were gathered to prove that continental drift did, nevertheless, occur in the Phanerozoic. Similarly, Eduard Reyer developed a clear concept of glide tectonics (Gleitfaltung) through observation and experimentation, but his ideas conflicted with the prevailing contraction theory which was then strongly supported by his teacher and later colleague Eduard Suess (1831-1914). Custom, inertia of thinking, and authority caused a rejection of Reyer's ideas by most of his contemporaries. Disappointed, Reyer devoted his later years to social reform, to the founding of public libraries, and to various philosophical problems. Only once, because he was deeply convinced of the correctness of his ideas, did he turn his efforts and his genius to the fundamental problems of geology. Geologische Prinzipienfragen, his last book on geology, has now been translated into English: it represents a matured concept of geology at the beginning of the twentieth century. Reyer's book is of great value for two major reasons: first, it contains many examples of unbiased observation, clear inductive thinking, and verification by means of experimental tests. Secondly, by stressing the role of gravity as a driving force, it marks a milestone in the development of structural geology.