Dictionary.com
Thesaurus.com

gumbotil

American  
[guhm-buh-til] / ˈgʌm bə tɪl /

noun

Geology.
  1. a sticky clay formed by the thorough weathering of glacial drift, the thickness of the clay furnishing means for comparing relative lengths of interglacial ages.


gumbotil British  
/ ˈɡʌmbətɪl /

noun

  1. a sticky clay formed by the weathering of glacial drift

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of gumbotil

1915–20; gumbo + til, variant of till 4