This is an Earthcache – as such, there is no physical cache. Instead after examining the building stone used in the Luray Singing Tower at the posted coordinates you will answer 4 questions and message me the answers.
LURAY SINGING TOWER
The Luray Singing Tower, officially known as the Belle Brown Northcott Memorial, was erected in 1937 in memory of Colonel T.C. Northcott's wife. Built of sandstone from Massanutten Mountain, this is a carillon tower 117 feet high and 25 feet square at the base. It has 47 bells with the largest weighing 7,640 pounds and the smallest being 12.5 pounds.
WHAT IS SANDSTONE?
Sandstone is a type of sedimentary rock composed primarily of sand-sized grains of mineral, rock, or other organic material. It is found throughout the world and is mined for use in construction. Sandstone contains a material that bands the sand grains together known as a cementing material, which contains silt or clay sized particles filling in the spaces between the grains of sand.
The grains of sand in sandstone have been reduced to their sand size through weathering, and they are transported and deposited via water, wind, or glacial action. Sandstone may contain larger sized grains, such as granules, but the rock would still be classified as sandstone if the primary component is sand-sized grains. The time and distance these sand grains have traveled will vary. If the sand is deposited near its source, the composition of the sandstone will more closely match the composition of the source rock. The longer the distance the sand grains have traveled will likely give the sandstone a more varying composition. More rounded grains indicate greater weathering and are an indication that the sand likely traveled a greater distance from its source rock.
The different colors seen in sandstone contribute to its uniqueness. Typically sandstone ranges in color from an off white, to tan, and to brown. Pure quartz is very light in color, so lighter colored sandstone would indicate a high quartz content and a low feldspar content. Feldspar has more of a dark amber color, so a greater feldspar content would tend to make the sandstone darker. Other colors that appear are indications of different minerals within the sandstone. For example brown, red, and orange would indicate the presence of iron, or purple would indicate the presence of manganese.
MASSANUTTEN SANDSTONE
Looking 2 miles west from the posted coordinates you can see the Massanutten Mountain Cluster in the distance. Towering just under 3000 feet, this mountain in the center of the Shenandoah Valley is dominated by sandstone and supported by shale. It’s Silurian in age and deposited after the Taconian Orogeny ebbed. When Africa collided into Virginia it initiated a phase of intense mountain building called the Alleghanian Orogeny. It was then that these quartz sandstone layers were compacted and folded into a syncline.
A syncline is a downward-curving fold, with layers that dip toward the center of the structure. On a geologic map, synclines are recognized by a sequence of rock layers that grow progressively younger, with the youngest layers at the fold's center or hinge followed by progressively older layers outward. Therefore, a reverse sequence of the same rock layers occurs on the opposite sides of the hinge. The synclinal structure of the mountain gives it its characteristic shape.
Massanutten sandstone is named for the mountain it is from. It’s quartzite is tough and stands up well to weathering. Rocks of the formation vary in local characters, mainly in color, thickness, and degree of silicification, but white and red quartzites prevail. Basal beds are alternating dark sandstones and shales, succeeded by white and gray quartzites, which give way to thin-bedded red and brown sandstones and shales.
REFERENCES:
1. "Syntectonic Deposition of Lower to Middle Siluran Sandstones, Central Shenandoah Valley, Virginia", Roberts, P. & Kite, M., Virginia Minerals Vol. 24, February 1978,, pages 168-169, 1923, dmme.virginia.gov
2. Notes on the stratigraphy of a portion of central Appalachian Virginia, Darton, N.H., 1892, American Geologist, v. 10, p. 10-18, ngmdb.usgs.gov
3. Luray Singing Tower, website luraysingingtower.com
4. Massanutten Special, WHAT THE ROCKS TELL US, MAY 9, 2012, Blog whattherockstellus.blogspot.com
5. The Geology of Massanutten Mountain in Virginia, Arthur Coe Spencer, 1896, hanse books
LOGGING REQUIREMENTS:To log this Earthcache: Read the geology lesson above. Answer all four questions posted below. Answers can be sent via e-mail or messenger contacts on my Geocaching profile. Do not post the answers to the questions in your logs.
QUESTION 1. Grains of sand in sandstone have been reduced to their sand size through what process?
QUESTION 2. Observe the stone. Judging by the color does this stone have a low quartz content and a high feldspar content?
QUESTION 3. Are there any indications that iron is in this stone?
QUESTION 4. Do you see any granules in this sandstone?
OPTIONAL PHOTO: Posting a photo that readily indicates that you (and anyone else logging the find) are at the location.
Placed by a proud member of both
Awesnap has earned GSA's highest level:
