The Unknown Facts of Limestone
Posted on May 2, 2017
Limestone is one of the many varieties of Sedimentary rocks. This rock primarily consists of calcium carbonate in the formation of a mineral calcite. The rock forms mainly under the shallow, warm and clear water bodies. This organic rock forms by the accumulation of the calcium-based organisms like corals, shells, algae and excretions of marine creatures. Limestone formation also takes place with the precipitated accumulation of ocean water and lake water. Below are the details of the two environments facilitating the formation of Limestone:
The Evaporative Environment
Limestone formations take place through evaporation. The formations are called stalactites and stalagmites and speleothems. The droplets of water seep down from the caves through several pores and fractures. Before dropping on the floor, they might even evaporate. After evaporation, these droplets leave behind depositions of limestone. These depositions later dissolve in the water and go through a chemical reaction on the ceiling. Several years of this process facilitates the formation of limestone structures on the ceiling as well as on the floor. The formations on the floor facing upwards are known as the stalagmite.
The Marine Environment
The formations of Indian limestones under marine environment take place through the accumulation of organic marine animals with calcium as their main component. The examples of these animals are shells, muscles, corals, etc. The fecal droppings of the marine animals aid in the formation of the limestone. Limestones are also great sources of marine fossils because the rocks entrap the living as well as the dead carcasses of the organisms and preserve them for many years. The biggest example of these is Cretaceous fossils of millions of years ago telling us about the creatures of that period.
Below are the details of top three varieties of limestone:
- Coquina: Lightly bonded variety of limestone made up of debris of broken shells
- Chalk: A soft variant of limestone with white or gray color formed of microscopic organisms and remains of the marine bodies.
- Tufa: This variant occurs in the calcium rich waters in lakes, hot springs, etc.