loess vs polder

loess

noun
  • Any sediment, dominated by silt, of eolian (wind-blown) origin 

polder

noun
  • An area of ground reclaimed from a sea or lake by means of dikes. 

verb
  • To reclaim an area of ground from a sea or lake by means of dikes. 

How often have the words loess and polder occurred in a corpus of books? (source: Google Ngram Viewer )