Limestone erosion rates measured at 0.5-1 mm per year. Hodgekin 1964 study: intertidal limestone erodes at 0.5 mm per year in California Point Peron, Australia study: 1 mm per year in intertidal zone over 9 years Iron/steel spikes driven into cliff faces to measure retreat rates

Multiple scientific studies establish limestone erosion rates: Hodgekin's 1964 California study found 0.5 mm per year in intertidal zones, Point Peron in Australia measured 1 mm per year over 9 years, and 1875 Tombstone studies showed 1 inch per 500 years in freshwater. The US Bureau of Standards reported 1 mm per 100 years on rooftop exposure for oolitic limestone. At these rates, 2 feet of erosion requires 1,200-1,600 years in high-energy environments. Interestingly, soft limestone erodes around harder argillaceous layers, creating measurable relief over time.

Key Facts

  • Hodgekin 1964 study: intertidal limestone erodes at 0.5 mm per year in California
  • Point Peron, Australia study: 1 mm per year in intertidal zone over 9 years
  • Iron/steel spikes driven into cliff faces to measure retreat rates
  • Tombstone studies (Geological Magazine 1875): 1 inch per 500 years in freshwater environments
  • US Bureau of Standards (1930): oolitic limestone loses 1 mm per 100 years on rooftop exposure
  • At these rates, 2 feet of erosion requires 1,200-1,600 years in high-energy environments
  • Soft limestone erodes around harder argillaceous layers creating measurable relief

Source: The Age of the Pyramids with Randall Carlson by Brothers of the Serpent