*This EarthCache is available from 7:00 AM to Sunset each day.*
Logging Requirements
Here you will observe the Fall Line as the Tar River flows from the Piedmont of North Carolina towards the Pamlico Sound on the Atlantic coast. Your task will be to answer the following questions:
1. At GZ (posted coordinates), describe the soil that you observe. Would you say you are in the Coastal Plain or the Piedmont at this location?
2. What specific geological features do you observe at GZ that tell you a fall line exists here?
3. What is the difference in elevation between GZ and Stage 2?
4. In your log, please post a photo of yourself or a personal item with one of the features you mentioned in #2 in the background.
Please send your answers to the above questions within 14 days of logging your find. Failure to send answers and post a photo within this time frame will result in your log being deleted.
Geologic History of North Carolina
The Fall Line is a geologic boundary marking the prehistoric shoreline of the Atlantic Ocean as well as the division between the Piedmont and Coastal Plain regions of the state. To understand how the Fall Line was formed, we must consider the geological forces that created North Carolina. The geology of North Carolina, like most of the southern states of the Atlantic seaboard is divided into three major regions. These are from west to east, the Mountains, the Piedmont, and the Coastal Plain:
-- The Appalachian Mountains are among the oldest mountains on earth. Old Appalachia in the Blue Ridge contains rocks that are older than life on earth, some dated over 1.8 billion years old. Over the course of hundreds of millions of years, due to the process of plate tectonics, ancient super continents collided and separated in the process that led to the formation of the North Carolina mountains. After formation, the Appalachians were as high as the Alps and the Rocky Mountains, but were reduced in height by millions of years of erosion.
-- The Piedmont begins at the foothills of the mountains; the word comes from the Latin for foot and mountain. Approximately 300 to 250 million years ago, the last major event in the geological history of the Piedmont was the break-up of the supercontinent, Pangaea, when North America and Africa began to separate forming the Atlantic Ocean. Large basins formed from the rifting were filled by the sediments eroded from the ancient mountains. Piedmont soils are high in clay content.
-- The geology of eastern North Carolina is dominated entirely by the Atlantic Coastal Plain which resulted from sediment eroded off the Appalachian Mountains. Beginning in the Cretaceous Period, rivers and streams transported sediment from the mountains to the coast, forming successive layers that fanned out across the gently sloping continental shelf and built up the Atlantic Coastal plains.
What is a Fall Line?
The Atlantic Seaboard Fall Line, is a 900 mile escarpment where the Piedmont and Atlantic coastal plain meet in the eastern United States. The Fall Line is called so because it is the point where rivers create waterfalls or rapids as they flow from the higher elevation of the Piedmont to the lower Coastal Plain. This change in elevation causes the river to “fall."
Source: US Geological Survey
In the eastern United States, there is a major Fall Line between the metamorphic and igneous rock of the Appalachian Piedmont and the soft sediment of the Atlantic Coastal Plain. This line was important to early European explorers because it marked the limits of river travel for ships. In addition to Rocky Mount, North Carolina, other cities that developed along this Fall Line included Trenton, New Jersey; Philadelphia, Pennsylvania; Richmond, Virginia; Columbia, South Carolina; and Milledgeville, Georgia.
The Fall Line serves as a geologic boundary that separates the soft sediments of the Coastal Plain from the hard bedrock of the Piedmont. The Coastal Plain soils are light-colored, sandy, and rich in limestone, and phosphate. The Coastal Plain, North Carolina's largest geologic region, accounts for about 45% of the State. Topography is mostly flat, but there are a few hills in the Coastal Plain because erosion has been uneven on the sedimentary formations. In the Piedmont, soils are a reddish clay and, topographically, the land rises gradually in elevation towards the mountains to the west. The Piedmont plateau runs east of the Appalachian Mountains and is at its widest (150 miles) in North Carolina. The eastern Coastal Plain is formed through the erosion of the Appalachian mountain ranges to the west and the loose soil continually erodes from rains and stream flowing to the ocean.
History of Rocky Mount Along the Fall Line
Scots and English traders encountered indigenous people here at the falls of the Tar River in the mid-1700s. Colonist began settling along the Fall Line as it provided a source of energy to power mills. In 1757 a Baptist Church was established at the falls by Reverend John Moore and Joshua Lawrence. In 1816 a post office was established at the falls of the Tar River. This was the first documented use of the name “Rocky Mount”. Two years later, in 1818, the second cotton mill in North Carolina, Rocky Mount Mills, was constructed.
On the way to the second waypoint you will see a historical marker, installed by the Daughters of the American Revolution, which records the site of Donaldson’s Tavern, a stage coach station of the Overland Trail which was located on the opposite bank of the river. LaFayette was entertained here while on his southern tour in 1825.
The railroad arrived about two miles east of the Fall Line in 1839. The economic center of Rocky Mount now moved to the railroad tracks as transportation of goods shifted from waterways to railroads. The Wilmington and Weldon Railroad was the longest continuous track in the world at that time. The county line of Edgecombe and Nash counties was moved to the railroad track resulting in Rocky Mounty being located in both counties. Rocky Mount was incorporated in 1867. Rocky Mount Mills, along with the nearby Stonewall house, is on the National Register of Historic Places.
The Fall Line remains important in the modern day for the measurement and management of pollution in North Carolina's rivers. The difference in soil types and water flow on either side of the Fall Line allows scientists to study the effects of pollutants introduced into the rivers, serving, in part, as the basis for various pollution-related regulations.
Thanks to Seemyshell for highlighting this Earthcache on The Geocaching Podcast on Christmas Day, 2024.
Sources
Encyclopedia Britannica
Jim Fowlkes, “The Fall Line"
National Geographic
Paleontological Research Institution, "Geologic History of the Southeastern United States"
US Geological Survey
Virginia Places, “The Geology of the Fall Line”
William S. Powell, ed., "Encyclopedia of North Carolina"
World Atlas