|Originally published in Dec. 1964 as Kansas Geological Survey Bulletin 169, 636 pages (2 vols.).|
The idea for the "Symposium on Cyclic Sedimentation" was born many years ago, but the final plans were not formulated until November 1961 at a meeting in Cincinnati attended by seven of the authors. At that time, July 1963 was set for submission of papers but later it was necessary to extend the deadline to January 1964. Many of the authors found that they could not express their ideas in a limited number of pages and so that limit (within reason) was dropped. Because both these restrictions were lifted, additional time was necessary to process the contributions. The extra time was worth the delay. The Symposium will record, in years to come, mid-20th Century thoughts on cyclic sedimentation by North American authors. It is a major contribution on the subject.
Just since formulation of plans for the Symposium, many exciting things have happened in science--men "walking" in space, rocket probes into the solar system, routine use of second-generation computers, lasers and all their ramifications, and all sorts of specialized electronic equipment have come into use. In the subject of cyclic sedimentation, likewise, progress continued--symposia were held, papers were published, a book on the subject is being prepared, and simulation of cyclic deposits is being explored using high-speed, electronic computers. No doubt, interest in the subject is being generated and because of this, much will be learned about this most interesting and important natural phenomenon.
No more fascinating field for research and speculation exists within the entire domain of stratigraphy (Weller, 1956).
In addition to extending the deadline and allowing extra length to papers, processing of the manuscripts was complicated by editorial and printing problems. Not the least of these was the absence of the editor for a year away to England to study "Old World" cyclothems. In my absence, the lackluster work of proofreading, carrying on correspondence, manuscript checking, etc., was carried on admirably by Sally Liggett Brown, Nan Carnahan Cocke, and Gary F. Stewart. I am indebted to them for their interest and unselfish and enthusiastic help in making this contribution better. Other Kansas Geological Survey personnel also graciously helped in many ways.
Manuscripts insofar as possible were styled in Kansas Survey form. Attempts were made, at least, to make each manuscript consistent. It is hoped, however, that the high caliber of the technical content of the articles will completely overshadow any editorial inconsistencies and inadequacies.
Here, then, is hopefully a useful contribution to an important aspect of geology.
Daniel F. Merriam
It is appropriate that the State Geological Survey of Kansas should celebrate its Centennial Year with a comprehensive symposium on cyclical sedimentation. Rocks of Pennsylvanian and Permian age in Kansas have provided some of the world's best examples of cyclical sediments. The contributions of the 45 authors contained in this symposium bring up to date the state of knowledge on cyclical sediments and processes in the United States. Far from solving all the problems presented by study of the rocks, the symposium authors point the way with new approaches and techniques and evaluation of old ideas to the need for continued research.
Frank C. Foley,
During recent years, the Kansas Geological Survey has directed its efforts toward two important goals. The first is concerned with the assemblage of information for synoptic publication on a systemic basis; the second is concerned with reinterpretation of the sedimentary environments. This Symposium on Cyclic Sedimentation is therefore consistent with the goals of the Kansas Geological Survey and further, is a fitting vehicle to celebrate the Centennial Anniversary of the Kansas Geological Survey.
Cyclical successions of sedimentary rocks have, for several decades, aroused the interest of geologists throughout the world and have been the subject of description and conjecture in numerous publications. These cyclical successions are perhaps nowhere better exposed than in Kansas where Pennsylvanian and Permian rocks are judged to be cyclical successions in large part. Some papers in this symposium will contribute significantly to understanding of these rocks and thus contribute to our goal of synoptic publication on a systemic basis.
Other papers support our goal of reinterpretation of sedimentary environments by concern with reduction of large masses of numerical data, the design of well-conceived experiments, and mathematical analysis of physical and chemical characteristics of these cyclical successions rather than concern with pure description.
Since the very beginnings of the science of geology, geologists have generated models to explain observable phenomena. Often, the model was based upon an experience factor, and one could look for and recognize a pattern in information that could be related to previously encountered models. However, the generation of a model is not always simple because problems are rarely simple, and one may be faced with the evaluation of many interacting parameters. A cyclothem is a model that attempts to explain the orderly succession of cyclical sedimentary deposits. The model involves a sequence of environments characteristic of marine transgression and regression characterized by minor changes in the elevation of land surface or sea level. However, this simple model has rarely been adequate to explain the complexity of most cyclical successions and further, the model has not been seriously tested.
Our notions about the tectonic and stratigraphic boundary conditions of sedimentary environments, for example, have long been controlled by models that may have outlived their usefulness and only by imaginative and systematic studies can we look to new models. Radiographic studies have shown that so-called homogeneous beds are rarely homogeneous and, in fact, exhibit all of the complexity of their more obvious associates. Systematic studies of cyclical successions should likewise throw new light on sedimentary environments. The microstructures of these rocks have assumed increasing importance in reinterpretation of these environments. In addition, new and powerful tools should aid in this reinterpretation. For example, a group working in the Kansas Geological Survey is using the computer along with two-dimensional Fourier analysis in order to examine the frequency spectrum of rock parameters, separate noise from the frequency spectrum, and develop numerical descriptors.
It has been tacitly assumed that most cyclical deposits are approximately synchronous in time. It may be that this aspect of the model is inaccurate and a model might be derived that would show synchroneity of different lithological units within the same cyclical succession. If this assumption is valid, then evidence should be found through close examination of sandstone units and in very detailed studies of microstructures within the shale units. It has been assumed that most even-bedded shales represent deposition on an essentially horizontal surface. These laminations may result from unloading, and shale units may exhibit all of the complex cross-bedding and other structures of other stratigraphic units.
This symposium is therefore especially significant because it serves to demonstrate interest in testing the cyclothem model and renewed interest in the whole problem of periodicity in earth history. The contributors to this symposium likewise are the catalysts for re-examination and reinterpretation of sedimentary environments.
William W. Hambleton,
Kansas Geological Survey
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Web version updated Sept. 29, 2004. Original publication date Dec. 1964.