Earth\u27s Place in Space

I\u27ve always thought that a story should start at the beginning. Since this book is the story of Earth, we will start at the beginning. According to the astronomers, in the beginning, there was no need for geology because there were no minerals or rocks; there was no Earth; there was no Sun; there were no stars or planets. According to the astronomers, there was a time when even our present universe didn\u27t exist. In the 1920s, the Belgian astronomer Georges Lemaitre hypothesized that everything presently contained within the entire Universe was once compressed into in a sphere he called the primeval atom ; a sphere that was possibly the size of a golfball ! As you might suspect, the conditions of temperature and pressure that would have existed in that golfball-sized sphere were so extreme that matter as we know it could not possibly have existed. Even the atoms of which matter is made could not have existed; even the parts of the atoms would have not survived such conditions. What then, was contained within such a sphere? According to Lemaitre, his primeval atom contained quarks which physicists consider the most basic of all atomic particles that they are the smallest subdivision of matter. Then where did the Universe come from? The astronomers say that about 13.7 billion years ago, Lemaitre\u27s primitive atom exploded and all of the quarks were released into space; an event cal1ed the Big Bang. The term Big Bang, by the way, was coined as a derogatory term by a leading astronomer of the 20th century, Fred Hoy]e, who refused to accept such an origin

Eons, Eras and Periods

A discussion of eons, era, periods and epochs of the geologic time scale

A Geology Field Trip

oduction to Field Trip I had several objectives in mind when I prepared this field trip. I want to develop in you an interest, an understanding, and an appreciation of geology of the region. I want to show you differences between three of the basic physiographic provinces within Appalachia, the Low Plateau, the High Plateau, and the Appalachian Mountain Section of the Valley and Ridge Province. I also want to show you the role that the kinds and structures of the underlying rocks plays in the formation of the topography of a region in order to have you better understand why the appearance of the land changes as you travel about the country. During the trip, you will also see excellent examples of the process of weathering as well as the erosive power of streams. The trip will visit several tourist areas and, in addition to their scenic beauty, you will learn that they represent excellent examples of important geologic features

The Cretaceous Period

A global rise in sea level occurred during the Cretaceous; as a result, sea level stood as high during the Late Cretaceous than at any other time in the Phanerozoic history of Earth. Although Pangea had begun to breakup during the Early Mesozoic Era, the smaller continents remained tightly clustered at the beginning of Cretaceous time. The continued breakup of Pangea and the dispersion of the newly created continents were among the most important events that occurred during the global geography of the Cretaceous. Especially important was the breakup of Gondwana. Gondwana was still intact at the beginning of the Cretaceous. However by the end of the period, South America, Africa, and India had all become individual continental masses; only Antarctica and Australia remained attached to each other

Coal Geology: The Origin of Coal

Coal forms from the tissues of plants with the major contributor being the woody tissues, cellulose and lignin, from trees growing in fresh-water wetlands. Land plants first evolved during the early Devonian and by the end of the period had adapted to most terrestrial environments. Beginning in early Pennsylvanian time, vast portions of the eastern portion of Laurentia were covered with coal-forming swamps and bogs, environments that were to be repeated throughout the remainder of the Paleozoic Era and again in the Jurassic, Cretaceous and Tertiary Periods. It was during these times that the combination of climatic conditions and wetland environments developed that were conducive to the growth and preservation of large volumes of wood-rich plant remains in the form of coal-forming peats, largely as a result of tectonic events that placed the continents into the proper climatic zones while at the same time producing the topographic settings under which vast peat-forming environments could be maintained for long periods of time. Some coals, such as those of the western United States, formed from peat that accumulated in land-locked basins created by the extensional tectonics that affected the region in the Mesozoic time while others such as our eastern coals formed in areas of low topographic relief along the margins of continents where they were near to but, as we will see later, were not chemically influenced by the marine waters

The Cambrian Period

The Cambrian Period extends from 570 million years ago to 505 million years ago. Notwithstanding the discovery of the Ediacara fauna, the Cambrian Period of the Paleozoic Era has historically been taken as the beginning of historical time based on the first appearance of abundant fossil remains. It is interesting to note, however, that where first described, the lower Cambrian was not very fossiliferous

Earthquakes

For centuries, earth scientists have known where the major earthquakes occurred. They also knew they occurred in the same locales as the most violent volcanoes, a fact that led to centuries of arguments as to which was the cause of the other. Now we know that they are not cause and effect; they are both associated with the convergent plate margins. During the mid-1900s, another major zone of both volcanic and earthquake activity was discovered, namely the divergent margins, the most important site being the oceanic ridges. Since then, we have also come to understand the occurrence of volcanic activity within the plates as being located over hot spots beneath the plates. All of this new knowledge has been the result of the theory of plate tectonic. In our discussions of volcanism, we learned that the observed difference in volcanic activity between convergent and divergent plates is due to the type of magma involved. We must now explain why the earthquakes associated with convergent plate margins are of much higher magnitude than those associated with divergent plate margins. For this we must review our discussion of stress and strain

The Permian Period

The Permian Period was a time of great crisis in Earth\u27s history. The Permian saw the final closure of the Iapetus Ocean that had formed following the breakup of the super­ continent of Rodinia in the late pre-Cambrian; the closure resulting in the formation of another super-continent, Pangea. It was during the Permian that two of Earth\u27s major mountain chains, the Appalachians and the Urals, were created. The period was one of climatic extremes. By the end of the Permian, Earth had not only experienced its most widespread glaciation but also the formation of deserts the likes of which had never been seen before. In addition to all of the physical events that were to occur during the period, the close of the Permian was the time of fue most severe extinction that has ever occurred in all of Earth\u27s history when more than 95% of all marine life was wiped out. The Permian was indeed, a crisis in the history of Earth

The Devonian Period

Until the 19th century, the rocks exposed throughout the provinces of Devonshire and Cornwall in southwestern England had long been considered to be Carboniferous in age because of their content of fossil plants. Closer investigation by Murchison and Sedgwick in 1836, however, showed that only the uppermost portion of these rocks contained fossil plants. Because the lower portion of the rock sequence was devoid of plant fossils, was highly deformed, and resembled the rocks of northwest Wales which they had recently studied, Murchison and Sedgwick assigned the rocks to the Cambrian System. However, local fossil collectors had submitted fossil corals collected from this same interval to Professor William Lonsdale who found them to be intermediate in evolutionary development between the corals of the Silurian and those of the Carboniferous. Based on this observation, Lonsdale suggested that this section of rock might be correlated with the Old Red Sandstone, a thick sequence of sandstones and shales located stratigraphically below the Carboniferous throughout much of Great Britain. It took two years before further study convinced Murchison and Sedgwick that Lonsdale was correct in his interpretation; it was Lonsdale who proposed the name Devonian for the system of rocks that existed between the Silurian and the Carboniferous. Unfortunately, the Devonian rocks in Great Britain are highly deformed by folding and faulting and are therefore very difficult t decipher. Perhaps the best sequence of Devonian rocks in the world are located in New York

The Geology of West Virginia

This is not meant to be a geology textbook but rather a discussion that will help you understand what you see around you every day or if you take a trip around the State. For example, you\u27re on your way to work or to class or you are going shopping. Most likely, you\u27re driving down a wide valley surrounded by hills. What do the hills look like? Why does the topography change as you go from one part of the State to another? In my opinion, of all the states that make up Appalachia, West Virginia is the most interesting geologically. The western portion of the State, say, Monongalia or Marion counties, are characterized by subdued hills with gentle slopes and rounded tops and adjoin broad valleys. On the other hand, the eastern counties such as Pocahontas or Pendleton counties a re more mountainous, the elevations of the ridges will be significantly higher than those to the west. The slopes of the hills will be much steeper, in some cases vertical or near vertical and the valleys will be narrow. Why are the two areas so different? You will discover that some of the reasons are quite simple. For one thing, the kind of rocks that underlie the topography in the two regions are different. In the western part of the State, the underlying rocks consist of a combination of soft shales and argillaceous sandstones that succumb rather easily to processes of weathering and erosion. In the east, on the other hand, the ridges are held up by sandstones such as the Tuscarora sandstone that are hard and highly resistant to weathering. Such sandstones cap sharp ridgelines such as North Fork Mountain and support vertical outcrops such as Seneca Rocks while the valleys are underlain by limestones as well as shales that undergo weathering and erosion more readily. It all makes for a different landscape scenario. In order to understand why landscapes of West Virginia change from place to place, we must take a closer look at Earth, the materials that make up Earth and the processes that are responsible for the changes in Earth\u27s surface that are constantly taking place. But where to start? As a geologist and teacher, I have always thought that to truly understand what we see around us we must start at the beginning. I do not mean for the manuscript that follows to be a highly detailed, scientific discussion, but rather a story of the events that have taken place that resulted in the formation of Earth and eventually to the landscape that surrounds you every day