Abstract Palaeobotanical studies in the NW of England could be said to originate with Mr William Barton and Charles Leigh in the latter part of the 17th century. These individuals merely noted the existence of fossil plant remains in the Coal Measure deposits around Lancashire. However, it was not until the 19th century before any real studies were carried out on the flora found within the Lancashire Coalfield. The Ravenhead collection is primarily made up of an Upper Carboniferous Langsettian flora, fish and bivalves with some insect remains. The collector was Liverpool Museum volunteer Reverend Henry Hugh Higgins and the collection was made from a railway construction site in 1870. The site exposed two coal seams known as the Upper and Lower Ravenhead Coals. The collection was exhibited at the British Association meeting held in Liverpool in 1870 and at once created a great deal of interest. W. Carruthers remarked upon the fine preservation and the importance of having material where the separate components can now with certainty be shown to be part of the same plant. Higgins published the first paper on the Ravenhead collection in 1871. A year later, museum assistant Frederick Price Marrat produced an extensive paper for the Liverpool Geological Society in which he attempted a more detailed description of the Ravenhead flora. This paper described 58 true and seed fern specimens with variations, nine types that included five holotypes and two syntypes. However, Marrat admitted he found identification of plant remains by relying on external features extremely difficult and Williamson’s methods of examining the microstructures of fossilized material were not yet in use. He published a further paper in 1872, listing the Sphenopsids found at the Ravenhead site. The bulk of the Ravenhead collection, including most of the types, survived the May 1941 blitz that virtually destroyed the museum. Unfortunately, all of the Ravenhead display material was lost in the fire.

Abstract Heat is critical for the occurrence of salt intrusion. Increased temperature greatly reduces the ultimate strength of salt and eliminates work hardening. When salt is heated above 400°F (205°C), it becomes soft and plastic and flows indefinitely with a pressure gradient of about 33-100 kg/cm 2 (460-1,400 psi). It is plastic during the entire process of intrusion, and even during extrusion at the surface. Thus, at the time of extrusion, salt can flow by simple gravity, like a “glacier,” as long as it remains hot. When buried at a depth of more than 25,000 ft, sedimentary salt becomes mobile because of the high temperature and behaves hydrodynamically; it moves laterally to places of lower overburden pressure, where doming or piercement occurs. Once flow is initiated, it will continue until the supply of salt is depleted or cut off, either by the coming together of the overlying and underlying strata or because additional supplies of salt have not been heated to the temperature necessary to maintain plasticity. The energy impelling the lateral or radial flow to the place of piercement can be attributed only to an imbalance in geostatic load of the overburden, but after piercement occurs, the geostatic load differential and the ever-increasing effect of buoyancy cause the salt to rise rapidly through the overlying strata. Buoyancy becomes an effective force only when the height of the intrusion has increased greatly. Buoyancy is not a requirement for intrusion, but it has a modifying effect. The emplacement of igneous masses such as volcanic plugs, granite batholiths, diamond pipes, carbonatites, and serpentine bodies (Gussow, 1962), and of such intrusive masses as mud volcanoes, shale diapirs, ice piercements or pingos (Gussow, 1954), and frost boils (Gussow, 1962), is similar to that of salt piercements. In all cases the prime motivating force for intrusion is the weight differential of the overburden, or geostatic load (Gussow, 1962). The writer postulates that salt-dome intrusion is a thermally activated process and that the rate of intrusion is rather rapid—probably catastrophic on a geologic time scale. The movement which has been interpreted as salt-dome growth is actually a measure of rate of compaction of the adjacent sediments. The fundamental mechanics outlined for salt diapirism are applicable to igneous intrusion generally, and to other forms of diapirism.

Abstract Earth scientists have literally been “moving heaven and earth” in an effort to discover the true cause of mountain-building revolutions, world-wide unconformities, world-wide extinctions of species, continental glaciation in what are now equatorial regions, and the presence of a warm temperate or subtropical flora in such polar regions as Greenland and the Canadian Arctic. The petroleum geologist is vitally interested in these questions because of their significance in evaluating the petroleum possibilities of such unexplored regions as the Arctic, Alaska, Antarctica, Australia, et cetera. Were these regions ever in the equatorial zone of reef growth, and when? The concept of crustal shifts (metastasy) is now more strongly supported than ever before by geophysical evidence, and such a mechanism offers the best and simplest explanation for many of the geological facts that have been accumulated. However, many questions remain to be answered and explained. Evidence is presented in support of a working hypothesis dealing with the rate of mountain building and the mechanics of mountain building; world-wide unconformities and their cause; and the distribution of paleoclimates. All require horizontal movements of the earth’s crust of considerable magnitude, and the problem is to find a suitable mechanism that can explain this. It is postulated that the cause of these horizontal shifts of the crust is erosion. It is further postulated that the shifts are sudden and that the glide plane was at or above the Mohorovi discontinuity and that metastasy is the explanation of mountain-building deformation and orogeny. Also dealt with are the origin of continents and ocean basins, the origin of the continental crust, the Mid-Atlantic Ridge, and the surface features of the moon.