There are three basic types of rock::
1) Igneous Rocks are crystalline solids which form directly from the cooling of magma (lava).
2) Metamorphic Rocks: The name comes from "meta" (change) and "morph" (form). Any rock can become a metamorphic rock.
3) Sedimentary Rocks: In most places on the earth’s surface, the igneous rocks which makes up the majority of the crust is covered by a thin layer of loose sediment. The rock which is made from layers of this debris (sediment ) get compacted and cemented together. Sedimentary rocks are called secondary, because they are often the result of the accumulation of small pieces broken off of pre-existing rocks.
There are three main types of sedimentary rocks: Chemical, Organic, and Clastic.
The formation of sandstone involves two principal stages. First, a layer or layers of sand accumulates as the result of sedimentation, either from water (as in a stream, lake, or sea) or from air (as in a desert). The stone quarried here at Government Island is fine grain sandstone (sometimes know as arenite). It is clastic stone (your basic sedimentary rock). It is composed of accumulations of clasts: little pieces of broken up rock which have piled up and been "lithified" by compaction and cementation.
The stone at this site is known as “Aquia Creek Sandstone” that is a type of brown to light-gray freestone that was used in building construction in Washington D.C. This is the only place on earth where it can be quarried. A quarry was established at Wigginton's Island (later called “Public Quarry”) on Aquia Creek by George Brent after 1694, providing stone for tombstones, houses, and churches in northern Virginia, including Gunston Hall, Christ Church in Alexandria, Virginia, Mount Airy in Richmond County, Virginia, and Aquia Church, as well as steps and walkways at George Washington's Mount Vernon. The land was purchased by Pierre L'Enfant on behalf of the federal government in 1791 to provide stone to build the nation's new capital city - Washington, D.C. The Island was then known as "Government Island", as it was owned by the federal government to construct public buildings. Because of the quantity and quality of the stone, its proximity to the Washington building site and its access to nearby waterways for transportation of the stone, this was a perfect location.
There are several quarries on Government Island, the coordinates are for the main rock facing. Once you arrive at the quarry, take a good look around, Can you see the tool marks in the rocks, or picture the amount of labor necessary to remove and transport the sandstone to the Washington building site.
To get credit for this cache please email us the answers to the following questions:
1. Looking at the information provided on the sign at ground zero, how wide were the “vertical channels or side trenches"? Do you see any examples of these trenches at this site?
2. Knowing that this sandstone is a result of sedimentation from water , take an altitude reading from your device at the sign what information do you get? Are you surprised by the reading?.
3. While facing the sign, turn to your right (South East approximately 129 degrees). Look at the rock face across the quarry, Do you see some almost horizontal indentations in the rock. Do you think these are natural or man made? Why? Now compare these indentations to the ones to your left 90 degrees. Does this change your mind? Why?
Outside of this area, this is a not well know walking trail but there is a lot of history right here in Stafford. Please enjoy this earth cache but also enjoy the park and all it offers. There are several traditional and letter box caches located in the park. Remember CITO.
Please observe all park rules and hours: (Mid-March through October 31: Monday - Sunday, 8:00 AM - 8:00 PM) (November 1 through Mid-March: Monday - Sunday, 8:00 AM - 5:30 PM). Remember take nothing and leave nothing but your foot prints.
