Examines some features of ice and snow that offer teachers and researchers help in understanding many aspects of igneous processes and configurations. Careful observation of such processes as melting, decay, evolution, and snow accumulation provide important clues to understanding processes by which many kinds of rocks form. (Author/JN)

Discusses causes of cyclicity in cratonic carbonate sequences and evidence for and potential significance of postulated primary calcite sediment components in past Paleozoic seas, outlining problems, focusing on models explaining existing data, and identifying background. Future sedimentary geologists will need to address these and related areas…

Describes construction/use of a device to simulate structures produced in fault zones of dominantly strike-dip motion. Apparatus modifications allow simulation of transtension and transpression as well as pure strike-slip fault motion. Illustrates formation of several structures using the apparatus, comparing them with natural examples. Includes…

Discusses theory of facies models (attempts to synthesize/generalize information about depositional environments), strengths/weaknesses of facies modelling, recent advances in facies models for siliciclastic sediments (focusing on fluvial, lacustrine, eolian and glacial environments, clastic shorelines and continental shelves, and clastic…

Describes a laboratory exercise using relief models, aerial photographs, topographic maps, and cone studies to determine depth and thickness of a concealed mineralized zone. (MA)

Discusses the presence and dynamics of continental glaciers in the domination of the physical processes of erosion and deposition in the mid-latitudes during the Pleistocene period. Describes the use of a sedimentary facies model as a guide to recognizing ancient temperate continental glacial deposits. (TW)

Reviews varying positions taken in the Cretaceous/Tertiary (K/Y) extinction controversy. Analyzes and contests the meteoritic impact theory known as the Alvarez Model. Presents an alternative working hypothesis explaining the K/T transition. (ML)

Offers instructions and geometrical data for constructing solids of the enantiomorphous symmetry classes 233 and 432. Provides background information for each class and highlights symmetrical relationships and construction patterns. (ML)

Describes a terrain model for geologic mapping which, when combined with exercises in rock description, Brunton compass manipulation, orienteering, and geologic report writing, allows students to refine skills needed for summer field camp. Advantages and limitations of the model and its use in a field course are also discussed. (BC)

Discusses trends, research activities, and conferences in geodynamics. These include topics on the lithosphere and lower continental crust formation discussed at a U.S. Geodynamics Committee workshop (Austin, Texas 1982) and symposia (each dealing with specific topics) sponsored by the Inter-Union Commission on Dynamics and Evolution of the…

Describes an inexpensive modeling technique for demonstrating large-scale displacement phenomena in rock masses, such as slope collapse and failure of underground openings. Excavation of the model material occurs through openings made in the polyurethane foam in the correct excavation sequence. (Author/SA)

Presents a model for demonstrating soil mass stabilization. Explains how this approach can assist students in understanding the various types of soil reinforcement techniques, their relative contribution to increased soil strength, and some of their limitations. A working drawing of the model and directives for construction are included. (ML)

Density-driven deep circulation is important in influencing geologic processes ranging from the dissolution of biogenic siliceous and calcareous sediments to the formation of erosional unconformities. A technique for dynamically demonstrating this process using an aquarium to enhance student understanding is described. (BC)

Presents a rock cycle diagram suitable for use at the secondary or introductory college levels which separates rocks formed on and below the surface, includes organic materials, and separates products from processes. (SL)

Describes a plexiglass and aluminum model of a Wadati zone suitable for classroom exercises and demonstrations in earth science to let students test the hypothesis that earthquake hypocenters near oceanic trenches tend to occur along planes that dip away from the trenches, toward associated island arc or continental mountain chain. (Author/JN)