Kliebhan, B. (1999) : The contribution of E.A. MARTEL (1859-1938) to the development of caving technique
For at least 30,000 years, Man has been visiting caves. During these early underworld excursions considerable distances were covered. Thus, about 3000 to 4000 years ago, American Indians penetrated more than 3 km into Mammoth Cave, Kentucky. In the Rouffignac … Weiterlesen →
