Skip to main content
Humanities LibreTexts

2.2: Geology of Caves

  • Page ID
    31723
  • Caves are openings in the earth caused by the erosion of the limestone (2.6). Limestone is a naturally occurring sedimentary rock and makes up 10% of all the rock on the planet. The limestone usually is composed of marine skeleton fragments from coral reefs and grains of silica, chert, clay, sand, and silt. The composition of limestone erodes quickly when in contact with water.

    The caves formed when melting glacier water or rain mixed with carbon dioxide forming carbonic acid, which reacted with the limestone causing it to breakdown. Over time, water erodes the limestone creating large areas of the caves that we know today. Rocks are unstable, and usually, cave entrances were blocked by erosion and rock slides, preserving the caves until other civilizations discovered them.

    clipboard_ec0bf9a54aa85da84d798498f405d8deb.png
    2.6: Limestone worn by wind, sand, and water

    Radio Carbon Dating

    Many people wonder how scientists establish the approximate dates of ancient art. In the late 1940s, the University of Chicago developed a method called radiocarbon dating, which relies on the amount of carbon located in the object about the amount of carbon in the atmosphere. The carbon, also known as C-14, is continuously formed when the cosmic rays interact with atmospheric nitrogen. Plants absorb C-14 and animals eat the plants; therefore, we all have C-14 in our bodies. Once an animal or plant dies, the C-14 begins to decay and has a half-life of 5,730 years, giving scientists an accurate dating process for objects up to 50,000 years using a mass accelerator spectrometer (2.7) to sample artifacts for dating.

    clipboard_e9a063fd00e5f871c351858a463796bdb.png
    2.7 Mass accelerator spectrometer for radio carbon dating
    • Was this article helpful?