$2.00 Geology and Physical Geography of the Strouds Run Area A publication of the Strouds Run Field Guide #1 Second Edition Geology and Physical Geography of the Strouds Run Area is a publication of the Friends of Strouds Run State Park (www.friendsofstroudsrun.org). It is published with the assistance of the Athens Conservancy (www.athensconservancy.org) and Athens Trails (www.athenstrails.org). Publications in this series: 1. Geology and Physical Geography of the Strouds Run Area 2. Spring Wildflowers of the Strouds Run Area 3. Invasive Exotic Plants of the Strouds Run Area 4. Ferns, Fern Allies and Lycopods of the Strouds Run Area 5. Woody Plants of the Strouds Run Area 6. Vascular Plant Checklist for the Strouds Run Area 7. Summer Wildflowers of the Strouds Run Area Bibliographic data: Knouse, John. Geology and Physical Geography of the Strouds Run Area. Friends of Strouds Run State Park, Athens, Ohio. Second edition, August 2013 (first edition published as Geology of the Strouds Run Area). 20 pages + cover, 9 photos, 7 maps, 2 tables, 1 diagram. Paperback. Copyright 2009, 2013 by the Friends of Strouds Run State Park, PO Box 514, Athens, Ohio, 45701 Acknowledgments: The Geology and Mineral Resources of Athens County, Ohio, by Myron T. Sturgeon and published in 1958 by the Ohio Geological Survey was an indispensible source of information for the stratigraphy, mineral resources, and related topics. W illiam E. Peters’ 1947 book, Athens County, Ohio, Volume 1, was indispensible in providing much historical and background data. Philip Cantino, PhD, was invaluable in proofreading and editing assistance. Geology of the Strouds Run Area General Geography Strouds Run State Park, about 2600 acres, mostly lies within the watershed of Dow Lake, the centerpiece of Strouds Run State Park. It includes only a portion of that watershed, (the total area of drainage that feeds the lake). The largest streams of the Dow Lake watershed are Strouds Run (once known as the Gillett Branch of Strouds Run), Labarthe Run (once known as the Labarthe Branch of Strouds Run), and Whitesel Run. Tucker Run and Gillette Run are major tributaries of Strouds Run (the stream), as well. The state park was originally the Athens State Forest, purchased starting just after World War II and continuing into the 1960s. The lake was filled in 1961 and the land became the state park. The area covered by this guide includes not only the state park, but also the City of Athens preserve lands (275 acres), the Athens Conservancy’s Blair Preserve (75 acres), and Tucker Run Preserve (49 acres). In addition, there are two small nearby tracts of the Wayne National Forest, totaling 315 acres, and trail access onto the nearby Baker Preserve, 284 acres, managed by the Athens Conservancy. All these lands are in Athens County, in southeast Ohio, embedded well within the unglaciated Geology of the Strouds Run Area 2 Allegheny Plateau. This plateau is characterized by rugged, steep-sided ridges and valleys, with ridgetops at fairly even levels. These ridges and valleys begin very suddenly at the eastern edge of the glaciated area that characterizes much of Ohio. The glaciers in that area left behind a very flat land, called till plains. The unglaciated hills then gradually rise in absolute elevation and in elevation difference (between valleys and ridges), culminating in the Allegheny Front. The Allegheny Front begins the Appalachian Mountains and is followed, travelling east, by the Ridge-and-Valley Appalachians, Shenandoah Valley, Blue Ridge/South Mountain range, Piedmont (roots of very ancient mountains), Coastal Plain, then finally the Atlantic Ocean. The land surface in southeast Ohio is called a plateau because the rock layers – called strata (singular: stratum) – are relatively flat, and the ridgetops are at roughly the same level. The ridge tops are the ancient remains of a more or less flat plain that was then lifted up, and the valleys eroded to their current level. This kind of feature has traditionally been called a “peneplain.” The plateau is a roughly north-south strips, from western New York state to northwest Alabama. The western front of the plateau is some sixty to seventy miles west of the park, and the Allegheny Front is around two hundred miles to the east of the park. Topographical Maps Strouds Run State Park may be viewed on USGS topo maps. This is short for “United States Geological Survey 7.5-minute topographic quadrangle.” A 7.5-minute quadrangle means that it spans 7.5 minutes of latitude and of longitude. “Topographic” means that the map is covered with lines drawn to show elevation above sea level. The park and associated lands lie mostly within the Athens quadrangle, which roughly covers the parts in Athens and Canaan Townships, with a small area in the Jacksonville quadrangle, which roughly corresponds with the part of the park in Ames Township. There are also coarser-scale USGS maps available, such as 15-minute maps, as well as locally-produced maps of the park with topographic layers, as shown on the next page. A topo map should have the “contour interval” marked on it. This is the vertical distance in elevation between any two successive contours. Heavier lines generally mark 100-foot contours or other significant intervals. An 800-foot contour passes through every point on the ground surface that is 800 feet above sea level. A map in a very flat area may have a contour interval of only one foot, while a map in a very mountainous area may have a contour interval of 100 feet or more. The map on the next page shows in detail an area of Strouds Run State Park, on the southwest side of Dow Lake. It shows a forked valley, opening to the right (east). The contour interval is 5 feet, with heavy lines at 100-foot intervals. The heavy line that lies entirely within the right half of the map represents 700 feet elevation, while the line that nearly touches the left-hand edge of the map is 900 feet elevation. Where the lines are closer together, as at “A,” slopes are steeper. Where lines are far apart, as at “B,” the ground surface is almost flat. The “rule of Vs” refers to the most sharply-pointed contour lines, as can be seen at points “C” and “D.” Compare these to points “E” and “F,” which are not as sharp. The sharply-pointed corners (“C” and “D”) are in the center of the stream channel, and point uphill. “E” and “F,” on the other hand, are the points of ridges jutting out. The “rule of Os” refers to anyplace where there is a closed circle, such as points “G” and “H.” When this is seen, the inside of the circle is the highest point – unless there are small lines, like centipede legs, on the inside of the circle, which indicates that it’s a hole in the ground. These are rare, however, and are mostly seen in cave country. Because the contour interval is 5 feet, it can easily be seen, by counting lines, that “G” is about 45 feet higher than “H.” Geology of the Strouds Run Area 3 Topographic maps of Strouds Run are available for sale at the park and other selected outlets. Historic Hydrology This area is part of the ancient Teays River drainage. The Teays River preceded the Ohio River, which was formed as a result of the last glaciation, but the Ohio River formation had little effect on the Dow Lake watershed. The New River and Kanawha River in West Virginia were the upper part of the original Teays River, which then may have followed Trace Fork, Mud River, and Guyandot River to the Ohio, then followed the current course of the Ohio for a short distance westward, continuing to the north into Ohio about eight miles east of the present Scioto River approximately along the course of the Little Scioto River, then swinging west near Jackson to then go north in the current Scioto River valley. The old course going to the west then gets lost under glacial till. This is why the Ohio River, instead, today drains this area: because the old Teays River course became blocked by the glaciers, and drainage waters had to find a new way out. In the meantime, an immense lake, termed Glacial Lake Tight, formed, until the Ohio River eroded a deep enough channel to drain it. In what is now Athens County, both Sunday and Monday Creeks are remnants of the pre-glacial Teays drainage (what geologists call “Chauncey Creek” was the predecessor of Sunday Creek, and “Luhrig Creek” was the predecessor of Monday Creek). Both of these creeks continued south of their present 4 Geology of the Strouds Run Area confluence with the Hocking River, to flow together to form the “Albany River”, which then followed much of the present-day course of lower Raccoon Creek, and then flowed into the ancient “Marietta River,’ which drained the upper Ohio River. The united river then flowed into the Teays River west of present-day Jackson. Geology of the Strouds Run Area 5 Present Hydrology The Strouds Run area features a dissected, dendritic drainage pattern with trellised aspects (see Labarthe Run, below). Dow Lake occupies about 160 acres and is fed by three main tributaries: Strouds Run, LaBarthe Run, and Whitesel Run. The first two are first-order perennial streams (also called blue-line streams), and the last is an intermittent stream. A perennial stream is one which flows year-round. A first-order stream is one that is primary, without other first-order streams flowing into it.