It’s in the Water: Karst, Limestone, and Calcium
Horses need at least 10 gallons of water a day! That’s a lot of water. Kentucky has water that is very good for horses because it contains calcium carbonate. You drink milk because it has calcium in it, and calcium builds strong bones and teeth. The calcium in Kentucky’s natural waters is good for the horses’ bones, too. So how did milk get into Kentucky’s water?
Grade Level
3rd and 4th Grade Science
Secondary Agriculture
Objectives
Students will develop an understanding of why certain geographical areas in Kentucky provide better habitats for breeding and raising horses.
Students will learn how natural weather events, such as acid rain, contribute to small changes on the earth’s surface.
Students will explore how weathering and erosion can leak calcium carbonate into the groundwater for animal consumption.
Students will construct an argument based on experimentation that limestone in Kentucky’s soil is released into the water through the process of weathering and erosion.
Next Generation Science Standards
3-LS4-3. Construct an argument with evidence that in a particular habitat some organisms can survive well, some survive less well, and some cannot survive at all.
3-LS3-2. Use evidence to support the explanation that traits can be influenced by the environment.
4-ESS1-1. Identify evidence from patterns in rock formations and fossils in rock layers to support an explanation for changes in a landscape over time.
4-ESS1-2. Make observations and/or measurements to provide evidence of the effects of weathering or the rate of erosion by water, ice, wind, or vegetation.
4-ESS2-2. Analyze and interpret data from maps to describe patterns of Earth’s features.
Background Information
Water from natural springs is one of the key factors that separates this state from others in regard to breeding and raising horses. They drink the water and eat water-fed grasses. Water is key to life, and it certainly is key to Kentucky’s horse industry, as well as other farm businesses. Large areas of Central Kentucky, the heart and home of many horse farms, is made up of an area known as karst. Karst is an area of land consisting mostly of a sedimentary rock called limestone, also known as calcium carbonate or calcite. This bed of limestone was formed when calm, shallow seas covered much of Kentucky. Tiny sea creatures and shells sank to the bottom where they decomposed, leaving the remains of their hard parts (bones and shells) that solidified over time, creating the present-day limestone. Over periods of time, the limestone has been weathered by acidic water (acid rain), dissolving the limestone into its elemental components, namely calcium and carbon. This calcium-rich water feeds the natural springs that fill the many creeks and ponds from which horses drink. Grasses absorb the calcium-rich water from the soil and are fortified by the ancient creatures.
Supplies/Resources
12 oz. clear plastic cups (3 per group)
distilled water
distilled white vinegar
limestone rock/chips
markers
measuring cup (1/4 cup)
2 buckets or large bowls for waste
strainer for cleanup
student information & lab worksheet (see button at the top)
pencil
Teacher Suggestions
This exploration lab can be done in groups or as a single student lab.
To save time on clean-up, have a large bucket labeled “Used Water” and a container labeled “Used Limestone.”
A simple strainer can be used by students to pour the water through to collect the limestone. This will keep students from “touching” any of the vinegar.
Curriculum Sponsors
Credits
Written by Jennifer McNulty
Design by Jennifer Elwell