I have always admired the stone façade of the buildings here in Jackson Park. As you look around you will notice that almost every building in this two-block area utilizes the same stone. B. W. Durham developed this section of Jackson Park in the 1930s. The first building in the area, located across the street on the corner of N. Cannon Blvd. and Jackson Park Road, was a one-pump gas station. Durham used the same stone on these buildings that was used on his personal residence now located on S. Main Street. According to the oldest document I have been able to find, the buildings in Jackson Park are covered in Tennessee stone. Local historians have differing opinions on what the stone is. I had one tell me that it was Tennessee Limestone, while another believes that it is Tennessee Sandstone.
This is where you come in. I need you, as an amateur geologist, to help me determine the type of stone utilized on these buildings.
Limestone:
Limestone is a carbonate sedimentary rock that often forms in shallow warm waters. The grains found in limestone are often composed of the skeletal remains of marine organisms, such as coral and mollusks. These organisms secrete shells made of aragonite or calcite, and leave these shells behind when they die. Shallow warm waters are where organisms capable of forming calcium carbonate shells can easily collect the needed ingredients.
Sandstone:
Sandstone is a clastic sedimentary rock composed mainly of sand-sized mineral particles or rock fragments. Most sandstone is composed of quartz or feldspar, both of which are silicates. Sandstone is formed from grains that may either be fragments of a pre-existing rock or be mono-minerallic crystals. These materials are typically cemented together by calcite, clays, or silica. Sandstone may be any color due to the impurities within the minerals, but the most common colors are tan, brown, yellow, red, grey, pink, white, and black.
Liesegang Rings:
Liesegang rings are colored bands of cement material observed in sedimentary rocks that typically cut across bedding. These rings are secondary sedimentary structures within a stone. They exhibit bands of minerals that are arranged in a regular repeating pattern. Liesegang rings are distinguishable from other sedimentary structures by their concentric or ring-like appearance.
What is the Difference Between Sandstone and Limestone?
Formation:
Sandstone is formed mostly from minerals found in sand or rock fragments. This process involves layers of sand gathering through sedimentation. Over time, these layers become cemented together by a binding material, such as calcite or silica, and compression.
Limestone predominately forms on a shallow, warm sea floor that is rich in calcium carbonate material. This material comes from the remains of marine organisms, such as corals and mollusks, and their fecal matter. Many times fossils of these marine organisms can be seen within limestone.
Appearance:
As the name implies, there is a sandy texture to sandstone. It also often has a visible stratification of layers. Both of these are easiest to see when the sand grains are comprised of different colors.
Limestone does not have the pronounced stratification pattern of sandstone. Because limestone is often formed from the shells and bones of marine organisms, it is usually a light color like white, tan, or gray.
Classification:
Sandstone is often classified based on the mineralogy of the grains and the type matrix found between the grains.
Limestone is classified based on either the composition of the grains, or the texture of the grains, contained in the rock.
Resources:
https://geology.com/rocks/limestone.shtml
https://geology.com/rocks/sandstone.shtml
https://sciencing.com/difference-between-sandstone-limestone-6060787.html
To log this EarthCache, send an email with the following information:
- Observe at least two blocks of stone on this side of the building. Are there any fossils present? If so, describe the fossils you see.
- From your observations, are layer stratifications visible in the stone? If so, please describe.
- From your observations, are Liesegang Rings present? If so, please describe.
- In your opinion, based on the reading and your observations, is the stone façade made out of Limestone or Sandstone?
- Post a picture of the most interesting stone block to you. It would be nice to see you in the picture; however, you or your group are not required to be in the picture.
