The plus of this series of 13 programs on 4 DVDs is that it allows scientists to illustrate geological analyses, principles, and theories, in classicalgeological settings or in their laboratory, and integrates various appoaches to try to resolve questions. The down side for me is that it is often too repetitive in reviewing what has been presented, is sometimes too elementary and simplistic, and sometimes presents controversial theories as generaqlly accepted facts. Also, there is perhaps too much emphasis on relatively recent spectacular volcanic and glaciation events at the expense of superficially more mundane, but equally important, geology(How many times was I presented with a spouting soda bottle as a volcanic eruption analogy?). Let's take a look at the specific topics covered, with my comments, as a non-professional geology enthusiast.
DVD#1 Begins with the massive non-tectonic-related lava flows in Siberia of about 250 MYA, which are generally believed responsible for the approximately simultaneous most devastating mass extinction in the history of life. This is a good presentation, noting the probable involvement of the coal layer through which much of the lava had to flow, and the probable involvement of ocean methane hydrates, but doesn't mention the probable involvement of other toxic volcanic substances, such as sulphur dioxide and mercury.
Next, is a rundown of of the continental glaciations of North America, mostly the last one. I found this presentation too elementary and incomplete. Finally, a program on America's gold deposits and mining. This is limited to deposits in CA and Nevada, which is OK, given the time constraints. The point is that different gold deposits were often formed in different ways, but with some commonalities. This was one of the more informative prograqms for me.
DVD#2 Starts with a consideration of how the Grand Canyon was likely formed. Generally informative;however, the viewer is left with indecision as to whether the 'spilled lake' theory or the traditional common sense down-cutting by the Colorado and tributaries theory was mainly responsible. Also, the probable importance of wetter times, hence much faster erosion, during glacial periods, is not mentioned. .. Next is a consideratin of the immense danger posed by a very active Mt. Vesuvius to the surrounding populated region. The various types of subduction-induced volcanic products are dramatized. I don't think it was mentioned that Vesuvius is but one of a whole chain of volcanoes in Italy resulting from the subduction of the African plate...Next is a consideration of theories and facts relating to the central question of how and when the earth and its major features of oceans and continents formed, along with the moon. I thought this was one of the best programs...Finally, a consideration of the geological and fossil history of the Sahara. Rather good, with a warning about the danger of overexploitation of the fossil water under that desolate surface. The importance of off shore oceanic sediment core analysis in documenting and dating various climate changes was emphasized.
DVD#3 Begins with Yosemite, primarily the Valley, but somewhat with the surrounding region. Very good program, presenting various theories and facts relating to the formation of the valley, and why this granite is often so resistant to erosion. In addition to Muir's widely disseminated valley glacier theory, Whitney's discounted dropped basin theory, Matthes's theory emphasizing river erosion, followed by glacial scupting, and Shaffer's more recent emphasis on increased jointing with uplift combined with exfoliation, are presented. .The Rockies program concentrated on the CO,WY and NM portions, illustrating how fossils indicate a former seabed and suggest a former higher Rockies. The sticky question of why the Rockies formed when they did is briefly dealt with, with evidence of a weak zone in the earth's crust here. It wasn't mentioned that mountains formed in this region long before the present Rockies. The peculiar route of certain WY rivers through mountain ranges is explained. But, it is not explained why WY mountains were once buried so deep by their sediments, nor why these sediments were later removed by erosion(presumably regional uplifting). The little appreciated subject of the Rio Grande rift is also explored. ..Lastly, the mostly good program on the 'Ring of Fire' around the Pacific, relies largely on field trips to various places in Alaska and CA to deomonstrate the general principles of volcanoes and earthquakes as among the most visible or dramatic surface features resulting from subduction of larely oceanic tectonic plates in this region. The importance of the physical and chemical pecularaities of the typical lavas produced by such valcanoes as distinct from those produced by Hawaiian volcanoes, for example, is emphasized. Mineral and gaseous peculiarities that point to the presence of seawater-derived carbon and water in the mantle below these volcanic areas is presented. The discovery of mid-ocean ridges as sources of new ocean crust is documented. However, the now largely discounted theory is presented that tectonic plate movement is fueled mostly by push from mantle convection currents, rather than by the pull of subducting plates.
DVD#4 Starts with the geology of Mt. Everest, and to some extent the whole Himalayan and Tibetan region. Too much time is spent climbing Everest for rock samples. Also, unfortunately, the impression is given that most of this mountain is composed of granite. Other sources indicate that most of the mountain is composed of metamorphosed sedimentary rocks below the yellow marble layer, with granite-intruded gneiss below this. Also, the use of high energy galactic cosmic ray-induced Beryllium 10 isotope concentrations in rocks as a proxy for erosion rates is related as 'cosmic sunburn damage' to the rocks: an unnecessary presumption of viewer ignorance of the concept of radioactive isotopes. Evidence is presented supporting the collision of India into Asia theory of Himalaya formation, also for the channel flow theory of mantle movement of collision-indiced granite uplift into the Himalayas. However, other tenable theories of Himalayan and Tibetan uplift are not presented. Finally, it is suggested that the rise of the Himalayas induced the recent cool period in the earth's history: another very controversial theory, as there are reasonable alternative explanations...Next, the description of the geological history of Death Valley is good, being comparitively simple to figure out. Even the mechanism of the gliding of the 'walking boulders' across certain flat or slightly uphill plains is presented. For a more complete story, I recommend the book "Geology Underfoot in Death Valley and Owens Valley"... Lastly, the eruption of MT. Saint Helens and its consequences is considered, for the obvious reason that it is the most recent large volcanic eruption in the continental US, thus has been well documented and studied. It was also unusual in that the primary volcanic blast occured toward one side, rather than vertically. Some years later, a volcanic eruption in the Caribbean largely duplicated the features of this eruption, and warning signs allowed the timely evacuation of many people in harms way, as here documented.