*Like all Earthcaches, this cache is virtual. So, you will not find a physical container here. Instead, by reading the description below and completing the logging tasks, you take away something immortal - new knowledge! So, as you read over this description and gaze at the rock outcrop in front of you, try to imagine yourself along a marine shoreline 420 million years ago...
Environmental History:
The trailhead and parking area of the Woodstock Fire Tower Trail is home to a large vertical slab of Massanutten Sandstone, (equivalent to the Tuscarora Formation along the Alleghenies). The Massanutten Formation is composed of a basal conglomerate unit under a quartzitic unit (Young & Rader, 1974). The quartzites are formed from white quartz and various colors of shales, particularly green shale, are found throughout the formation (Young & Rader, 1974). The Massanutten Formation is located only in the northern areas of the Shenandoah Valley and is significantly thicker than most Tuscarora Formation deposits, likely due to the Tuscarora representing areas more proximal to the Acadian Mountains of the time (Young & Rader, 1974).
Both the Tuscarora Formations and the Massanutten Sandstone were formed in the Silurian age. One notable ichnofossil, or trace fossil, found in the Massanutten Sandstone can be seen in the vertical slab at the parking area. These fossils are Arthrophycus, potentially Arthrophycus alleghaniensis, and were formed over 435 million years ago (Arthrophycus alleghaniensis, 2010). Arthrophycus sp. is a trace fossil, or ichnofossil, a type of fossil that represents the activity of organisms, rather than preserving body parts of organisms. A. alleghaniensis was likely created by segmented worm-like arthropods. They are common trace fossils located only in Silurian regions of the Appalachian mountains (McCoy et al., 2012). The arthropods created burrow systems throughout the sandstone that crisscross and are formed both parallel and perpendicular to the formation. The burrows typically have tapered ends, are anywhere from 1-6 inches in length, and are thought to have been formed in a marine environment (Hasiotis, 2014).
These trace fossils are important to geologists as they help to determine the paleoecological history, or ancient environmental situation of a location, including water table depth and historic land configurations (Arthrophycus alleghaniensis, 2010). The presence of these ichnofossils on the Woodstock Fire Tower Trail is helpful in understanding the history of the Shenandoah Valley around the time of the Precambrian and Cambrian eras when these rock formations were created. Around one billion years ago, the American and Eurasian plates collided to form the supercontinent Rodinia.
Over the subsequent 700 million years, the ancestral Atlantic Ocean (Iapetus Ocean) would open up as a result of the divergent boundary that ripped Rodinia apart. This ocean would begin to close and the plate tectonic situation in the Iapetus became dominated by subduction, eventually creating the next supercontinent, Pangaea. Three separate orogenies would take place before this ocean finally closed, the Taconian, Acadian, and Alleghenian Orogenies which were mountain-building events (Massanutten Sandstone, 2018).
The ancient environment associated with this location was involved in the Taconian plate movements of the Late Ordovician and early Silurian periods of the Paleozoic Era, approximately 440 million years ago (Diecchio & Fichter, 1988). The Massanutten Sandstone at that time was part of a fluvial system flowing across an ancient sand-rich beach coastal shoreline, indicated by structures consistent with the paleocurrents of an underwater environment (Diecchio & Fichter, 1988). For most of ancient history, this area was underwater, as can be seen in the presence of certain fossils and sandstone. The Massanutten Sandstone became exposed over time, eventually becoming the rock formations known in the Shenandoah Valley today.
References:
Arthrophycus alleghaniensis. (2010). Bald Eagle Geotec. http://www.baldeaglegeotec.com/geonotes/fossils/arthrophycus.htm#:~:text=Arthrophycus%20is%20the%20name%20paleontologists
Diecchio, R., & Fichter, L. (1988). The Taconic sequence in the northern Shenandoah Valley, Virginia. GeoScienceWorld. https://pubs.geoscienceworld.org/gsa/books/book/869/chapter/4861099/The-Taconic-sequence-in-the-northern-Shenandoah
Hasiotis, S. (2014). KU Ichnology. KU Ichnology. https://ichnology.ku.edu/invertebrate_traces/tfimages/arthrophycus.html
Massanutten Sandstone. (2018, May 10). Hiker’s Notebook. https://hikersnotebook.blog/other-articles/geology-and-earth-science/massanutten-sandstone/#:~:text=The%20sequence%20of%20events%20that
McCoy, V., Strother, P., & Briggs, D. (2012). A Possible Tracemaker for Arthrophycus alleghaniensis. BioOne Complete. https://bioone-org.ezlfcc.vccs.edu/journals/journal-of-paleontology/volume-86/issue-6/11-133R1.1/A%20Possible%20Tracemaker%20for%20Arthrophycus%20alleghaniensis/10.1666/11-133R1.1.full
Young, R., & Rader, E. (1974). Geology of the Woodstock, Wolf Gap, Conicville, and Edinburg Quadrangles, Virginia. Commonwealth of Virginia Department of Conservation and Economic Development Division of Mineral Resources. https://energy.virginia.gov/commercedocs/RI_35.pdf
Human History:
The Woodstock Tower was built in 1935 by the Civilian Conservation Corps using materials furnished by the Woodstock Chamber of Commerce (United States Department of Agriculture Forest Service). By 1933, the Great Depression had stolen the nation’s jobs and morale. So, President Franklin Roosevelt created the Civilian Conservation Corps (CCC) to combat unemployment and preserve our nation’s natural beauty. (Bell, 2020). The George Washington and Jefferson National Forests are home to hundreds of these CCC projects. These include, but aren’t limited to, the Elizabeth Furnace, Little Fort Recreation Areas, Powell’s Fort Organization Camp, and of course, the Woodstock Tower (Bell, 2020).
The Civilian Conservation Corps epitomized the single greatest conservation movement in the history of the United States. Not only did the CCC achieve numerous conservation projects, but it also restored the dignity of work to the young men of the Great Depression.
The CCC built the Woodstock Tower as part of their early fire detection initiative following a series of forest fires in the early 20th century (Forest History Society, n.d.). The fire tower was useful to detect smoke from far distances and pinpoint exact locations of fires in order for the local fire department to intervene.
Figure 1.
Woodstock Tower Aerial Image
Note. Hiking Upward. (2022). Woodstock tower aerial image. [Photograph]. Hiking Upward. https://www.hikingupward.com/gwnf/woodstocktower/
Figure 2.
Spirit of CCC by Harry Rossoll, 1938
Note. Browne, A. C. (2013). Spirit of CCC by Harry Rossol, 1938. [Photograph]. The Historical Marker Database. https://www.hmdb.org/m.asp?m=10158
References:
United States Department of Agriculture Forest Service. (n.d.). Woodstock tower observation site. https://www.fs.usda.gov/wps/portal/fsinternet/cs/recarea?ss=110808&navtype=BROWSEBYSUBJECT&cid=FSE_003738&navid=110240000000000&pnavid=110000000000000&position=generalinfo&recid=74047&ttype=recarea&pname=Woodstock%20Tower%20Observation%20Site
Bell, F. (2020, January 26). Birthplace of the CCC - Camp Roosevelt, NF-1. The Historical Marker Database. https://www.hmdb.org/m.asp?m=10158
Forest History Society. (n.d.). Fire Lookouts. US Forest Service Headquarters Collection. https://foresthistory.org/research-explore/us-forest-service-history/policy-and-law/fire-u-s-forest-service/fire-lookouts/
Questions:
After logging the Earth Cache, use the GigaPans and cache to answer these questions and respond in the log box or through the message center:
- What trace fossils can be found in the Massanutten Sandstone formation?
- What orientations are the ichnofossil burrows?
- You may find the following linked GigaPan images to be helpful here.
GigaPan 1.
GigaPan 2.
GigaPan 3.
- What kind of environment did the organism that created the burrows live in?
- Hint: The rock type is your clue!
- What do these trace fossils imply about the Shenandoah Valley?