Introduction
This earth cache will take you to Little Lake Park in Grand Rivers Kentucky. At the coordinates you will take you to two pieces of stone common to the area between the Kentucky Lake Reservior (Tennessee River) and the Lake Barkley Resevoir (Cumberland River). You will know the correct location when you are standing between a stone boulder and a stone bench.
Logging Tasks
A. Required - Send me the answers to the following questions in a message or email"
- What is the predominate color of the boulder and of the bench?
- What is the texture of the boulder and of the bench?
- Which stone shows exfoliation - the boulder or the bench?
- Which stone is composed of many fossil particles - the boulder or the bench?
- Which is limestone and which is sandstone?
B. Optional - Take a picture with the sign that is being "eaten" by a tree in the background.
Limestone vs Sandstone
Limestone and sandstone are not all that unusual. In fact, they can actually be found all around the world. As sedimentary rocks, they have a number of similarities. When looked at more closely, however, their composition and formation actually do set them apart from one another. So, what’s the actual difference between limestone and sandstone?
Limestone is a sedimentary rock composed mostly of calcite and aragonite, which are different crystal forms of calcium carbonate. It is a durable rock of medium hardness. Limestone is a fine grained rock and has a smoother texture than sandstone. It may or may not be clastic - composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus, chunks and smaller grains of rock broken off other rocks by physical weathering. Color ranges include: beige, brown, grey, white, and yellow. Limestone is not as water or acid resistant as other rocks and will easily weather through dissolving and exfoliation (flaking). It tends to be very stain resistant.
Sandstone is defined as a rock which is composed of sand-sized grains of various minerals mostly of uniform size and often are smooth and rounded. It is a very durable, hard rock. Texture varies depending on clast composition, but usually feels rough like sandpaper . Colors range from red, brown, and grey. It is much more water and acid resistant than limestone. Sandstones easily stain.
Regional Geology
Grand Rivers lies at the boundary between the Mississipian plateau (Penyroyal region) of central Kentucky and the Mississippi embayment to western Kentucky. Warsaw crops out discontinuously along the lower valleys of the Cumberland River (Lake Barkley) and Tennessee River (Kentucky Lake) in which Grand Rivers is located. Thickness of the Warsaw ranges from 170 to 300 ft, and averages about 200 ft. Micrograined to coarse bryozoan and crinoid fragments in a chalk-like matrix is characteristic with intervals of high-calcium stone.
In southern Livingston County, the Fort Payne is quarried at a site where it was protected by a thick cap of Warsaw Limestone. The Fort Payne
limestone exposed in the quarry is very fine to fine grained, siliceous, and cherty, with varied amounts of fossils.
Marine waters advanced and receded many times, which produced many layers of sandstone which lies above the limestone layers of the region. Clayton and McNairy sandstones are most common in this region of Kentucky.