HISTORY OF GEOLOGY FROM 1780 TO 1835 175 It is interesting to remark that a place like the Isle of Arran, near Glasgow, had exposures that were broadly compatible with both the Huttonian and Wernerian theories (see Figure 1) But unconformities such as the famous one examined by Hutton at Siccar Point (see Figure 2) could only be well explained in Huttonian terms And granitic veins, such as those famously examined by Hutton at Glen Tilt, and anastomosing Figure Sketch of the geology of the northern part of Arran The exposures can be accounted for in terms of either the depos ition of transitional rocks (schists) and Floeătz sediments round a central granitic core; or the intrusion of granite into sediments, forming a dome structure with partial metamorphism round the granite mineral veins, could hardly be accounted for by the Wernerian theory Reconstruction of Past Environments The chemist Antoine Lavoisier accompanied Guettard during his travels for the purposes of compiling a mineralogical map of France and acquired some knowledge of geology Lavoisier became interested in the conditions that might be expected to occur at the bottom of the sea, at different depths and different distances from the shore, with cobbles near the edge of the sea, sand further out, and fine sediment some distance offshore An idealized profile was published (1789) showing the occurrence of pelagic and littoral deposits Such different sediments could also be seen in the strata observed inland, and the analogies were clearly understood Thus we have the beginnings of attempts to reconstruct past environments on the basis of what was visible in the strata Work of a similar kind was undertaken in the Paris basin in the early nineteenth century by Alexandre Brongniart and Georges Cuvier (see below) They recognized marine and fresh-water sediments on the basis of the fossil shells they contained (fresh-water forms generally having thinner shells) The arguments were based on analogies made with modern forms Later, Charles Lyell (see below) realized that the processes of lime formation in freshwater lakes in his property in Scotland resembled similar depositions occurring in modern France Examination of coal deposits suggested hot and humid swamp conditions Or desert sandstones could be recognized for what they were The beginnings of palaeoecology occurred during the ‘hinge of history’ Figure Hutton’s Unconformity at Siccar Point, south east of Edinburgh ‘Old Red Sandstone’ with basal conglomerate lying almost horizontally on upright ‘schistus’ (Silurian greywackes) After Secord JA, Controversy in Victorian Geology Copyright ß 1986 by P U Press Reprinted by permission of Princeton University Press