Cold Stream – History In Rocks EarthCache
Cold Stream – History In Rocks
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Cold Stream – History In Rocks
Here you will discover a exposed section of Limestone in the Cold Stream Park, exposed when a road was placed here. Cold Stream Farm was the famous Kentucky horse farm, known earlier as McGrathiana, was the home of Aristides, the first winner of the Kentucky Derby.
Tasks: email or message me the answers to the following tasks/questions to demonstrate your understanding of the Cane Run Watershed Project. Please DO NOT include your answers in your online log.
1. How thick is the exposed limestone "cut" in height?
2. How many thick layers of limestone are there from the bottom to the top of the cut?
3. How wide are the boreholes used to expose the limestone?
4. Based on your observations, which member of Lexington Limestone exists at this location?
5. Briefly describe a fossil you discovered.
Lexington Limestone
The Lexington Limestone is the major rock unit exposed in the Inner Bluegrass region of east-central Kentucky surrounding Lexington. This limestone section contains variable amounts of silica in the form of chert or flint, as well as varying amounts of clay, silt and sand as disseminations, nodules, or layers within the rock. The primary source of the calcite in limestone is most commonly marine organisms. These organisms secrete shells that settle out of the water column and are deposited on ocean floors as pelagic ooze or alternatively is conglomerated in a coral reef. Another form taken by calcite is that of oolites which can be recognized by its granular appearance.
Travertine (a type of limestone found here at the site) is a banded, compact variety of limestone formed along streams, particularly where there are waterfalls and around hot or cold springs. Calcium carbonate is deposited where evaporation of the water leaves a solution that is supersaturated with chemical constituents of calcite.
The best exposed fossils in the limestone are on top of the limestone formation. Here you will find many types of fossils in several layers.
Curdsville Member
• base unit of Lexington limestone
• about 20 - 40 feet thick; composed of mostly thick layers of calcarenite limestone
• shale partings are thin; usually no talus pile of rocks to look through at the base of a cut.
• fossils can be spectacular, they are very sparse.
Logana Member
• not always present
• 0 to 50 ft. thick; exhibits repeating and fairly regular cycles of alternating limestone and shale
Grier Member
• thickest member, 100 to 180 feet thick,
• deposited in shallow, moderately agitated water
• recognized by its thin, irregular or nodular beds of limestone
• composed largely of broken fossil debris; fossil hunting in this member is
generally unrewarding
Tanglewood Member
• 60 up to 100 ft. thick
• forms much of the upper (surface) part of the Lexington Limestone in the Bluegrass region
• larger grain size than most other units of the Lexington
• cross bedded in some places; deposited in a turbulent, very shallow marine enviroment.
• fossils are almost always broken and abraded small hash fragments
Perryville Member
• 0 to 50 feet thick
• fossil collecting can be good in this member
Brannon Member
• 0 to 30 feet thick
• sometimes the limestone exhibits a ball-and-pillow structure and contorted bedding
• fossil collecting in the Brannon is generally poor
Millersburg Member
• 0 to 90 feet thick
• very obvious due to its shaley, nodular appearance and rubbly weathering
• excellent member for fossil hunting
This Geocache was approved by Lexington-Fayette Urban County Government Parks, code CP18e.
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