Geology topics
Publications and source records attributed to John Calvin Reed.
Geology is the science of the Earth-the study of the forces, processes, and past life that not only shape our land but influence our daily lives and our Nation's welfare. This booklet, prepared by two members of the U.S. Geological Survey, discusses how geologic phenomena are responsible for the magnificent scenery of the Teton region
No abstract available.
The Great Falls of the Potomac River has figured prominently in the purposes of men since prehistoric time. Long before John Smith reached the falls in 1609, groups of Indians from East and West met at this great river barrier to trade and perform ceremonies in honor of the spirit of the "Roaring Waters". As early as 1754, George Washington visualized the Potomac River as an important avenue of trade and communication with the interior. Records show that with the exception of Mount Vernon, Great Falls was perhaps as intimately associated with George Washington's everyday life as any other place in the country. As first President of the "Patowmack Canal Company," Washington frequently visited the working parties as they constructed the canal and lock system which skirted the treacherous falls on the Virginia side. Matildaville, a town of about 40 acres named after the wife of "Light Horse" Harry Lee and consisting of various dwellings, grist mill, market house, forge, sawmill, and tavern, sprang up along the banks of the canal. In 1802, the Patowmack Company canals were essentially completed, and hundreds of boats plied the river, bringing corn and wheat, coal and limestone, flaxseed and furs downstream from the mountainous region of Cumberland. Many of the boats were sold for lumber in Georgetown, thus sparing the boatmen an arduous upstream journey. After the establishment of the Nation's Capital, Great Falls became a popular scenic attraction for residents and visitors alike. But Great Falls was not always so easily accessible as it is today. In 1845, a newspaper columnist, after praising the beauty and historic interest of the region, added, "... the access to this interesting spot is, on both sides of the river, by the most infamous of roads and the accommodations for visitors anything but what they ought to be!" Visitors to Great Falls now number close to a half million annually and, because of this continuing and mounting interest, the U.S. Geological Survey has joined with the National Park Service in preparing this booklet for better understanding and enjoyment of the Great Falls of the Potomac River.
Explore the source record for details and available documents.
No abstract available.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
In the Blue Ridge Province of northern Virginia, Maryland, and southern Pennsylvania, Lower Cambrian beds are underlain by a thick sequence of greenstone and interbedded sedimentary rocks known as the Catoctin Formation. An area near Luray, Va., was studied to determine the thickness of the formation, its relationship to overlying and underlying rocks, and the original nature of the lavas from which the Catoctin greenstone was derived. There the Catoctin Formation lies unconformably on granitic rocks. Its basal sedimentary layer ranges from a few inches to 150 feet in thickness and contains pebbles of underlying basement rocks. The erosion surface beneath the Catoctin is irregular, and in several places, hills as much as 1,000 feet high were buried beneath the Catoctin lavas. No important time break is indicated between the deposition of the Catoctin Formation and the overlying Cambrian sediments. The original Catoctin lavas were basaltic and were probably normal plateau basalts. Columnar joints, amygdules, sedimentary dikes, flow breccias low-dipping primary joints, and other primary structures are well preserved.
Small deposits of native gold are present along an anastomosing system of quartz veins and shear zones just east of Great Falls, Montgomery County, Md. The deposits were discovered in 1861 and were worked sporadically until 1951, yielding more than 5,000 ounces of gold. The vein system and the principal veins within it strike a few degrees west of north, at an appreciable angle to foliation and fold axial planes in enclosing rocks of the Wissahickon Formation of late Precambrian (?) age. The veins cut granitic rocks of Devonian or pre-Devonian age and may be as young as Triassic. Further development of the deposits is unlikely under present economic conditions because of their generally low gold content and because much of the vein system lies on park property, but study of the Great Falls vein system may be useful in the search for similar deposits elsewhere in the Appalachian Piedmont.
No abstract available.
Explore the source record for details and available documents.
No abstract available.
Explore the source record for details and available documents.
No abstract available.
Explore the source record for details and available documents.