Cropmarks in main field crops enable the identification of a wide spectrum of buried features on archaeological sites in Central Europe

摘要

Buried (syn. sunken, sub-surface and sub-soil) archaeological features on arable land can frequently be discovered due to visually detectable changes in crop growth termed cropmarks. The aim of this paper was to demonstrate the range of features identified through cropmarks on aerial photographs in stands of main field crops in the Czech Republic. Low-altitude oblique aerial photographs of cropmarks were collected from an aircraft from a height of 300-500 m above ground during approximately 800 flight hours from 1992 to 2010. Some features discovered via cropmarks were excavated by standard archaeological methods. Around one thousand cropmarked sites were discovered. The highest density of archaeological sites was on sandy soils in dry lowland regions, and a substantially lower number on loess or clay soils or in regions above 350 m a.s.l. Cropmarks were best developed in barley (Hordeum vulgare), followed by wheat (Triticum aestivum), winter rape (Brassica napus) and lucerne (Medicago sativa). The most common archaeological sites discovered via positive cropmarks were ancient funeral and settlement areas, with many related features such as waste pits, sunken dwellings, post holes, ditches and graves. Abandoned roads were the most commonly negatively cropmarked features. Positive cropmarks represented 98% and negative only 2% of all recorded cropmarks. Archaeological features present beneath the modern arable horizon can irreversibly change sub-soil properties and growth of crops. Arable fields in Czech lowlands represent a unique archive of buried archaeological features, recording human activities in the landscape over the last 7500 years.