SATURDAYS AT 1 PM
Lectures are FREE for museum members — $5.00 for non-members.
April 6th: Mineral Twinning by Dr. Terry Panhorst (IMMG)
Minerals have regular atomic structures, which are expressed by the various repeating crystal shapes found in nature. Twinning occurs when two or more crystals of the same mineral are symmetrically intergrown, as defined by their respective atomic structures. There are a variety of different types of twins, some of which give particular minerals a characteristic shape or appearance. Twinning is frequently exhibited in many minerals, and examples of several common twin types will be shown using illustrations of different mineral specimens.
May 18th: It’s Not Your Fault: Mining Law, Geology, and How the West Was Won by Troy Lambert
June 1st: History of Geologic Discoveries in the American Northwest: 1960-2019 by Dr. Terry S. Maley, P.G.
Geologists started to seriously investigate northwest geology late in the 19thCentury; and, by 1960 all the major rock types and their associated structures had been mapped. However, the origin of most of these geologic provinces and related features were unknown. A breakthrough occurred in the early 1960s when Plate Tectonics rapidly replaced the Geosyncline concept—a now obsolete concept that served as an explanation for mountain belts for almost 100 years. After 1965, the unifying principles of Plate Tectonics led to a remarkable succession of new discoveries involving almost every part of the northwest, including Idaho. These discoveries will be illustrated and described in this presentation.