i 
TO THE 
REV. WILLIAM VERNON HARCOURT, 
F.R.S., F.G.S. 
WHO AS FIRST PRESIDENT OF THE YORKSHIRE PHILOSOPHICAL SOCIETY 
PROPOSED FOR ITS PRINCIPAL OBJECT 
l 
THE ELUCIDATION OF THE GEOLOGY OF YORKSHIRE, 
AND LABOURED EARNESTLY IN THE PROSECUTION OF IT ; 
AND 
THE REV. ADAM SEDGWICK, 
F.R.S., F.G.S. 
WOODWARDIAN PROFESSOR IN THE UNIVERSITY OF CAMBRIDGE, 
WHOSE GEOLOGICAL CAREER BEGAN WITH RESEARCHES 
IN THIS HIS NATIVE COUNTY ; 
THIS VOLUME 
IS MOST RESPECTFULLY DEDICATED, 
BY THEIR FRIEND AND FELLOW LABOURER, 
THE AUTHOR. 
