INTRODUCTORY LETTER. xv 
with the same subject embodied in Dr. Norwood’s Report, will all possess more or 
less interest. So also, in Dr. Norwood’s Report, will the mineralogical and orographic 
information, and the remarkable metamorphoses of the sedimentary strata on the 
north shore. 
Both the general reader and the geologist will probably find interest in the inci- 
dental chapter on that extraordinary and hitherto almost unexplored region, the 
Mauvaises Terres (Bad Lands); a region not only attractive to the naturalist by its 
rare wealth of fossil remains, but, in its natural features, perhaps unique throughout 
the world. 
In justice to those who have aided me in the Survey and in preparing mate- 
rials for this Report, I here state, that, but for the industry and perseverance 
they brought to the task, it would be still far from completion. Our working 
hours have usually been twelve, sometimes fifteen, per day; and even with such 
exertions, it has been with difficulty we have executed the necessary analyses, 
calculations, diagrams, sections, and charts, so as to present the whole in its pre- 
sent complete form, before the opening of the approaching session of Congress. 
In conclusion, I beg here to acknowledge the valuable and essential aid contri- 
buted on this Geological Survey by the following gentlemen :— 
Assistant Geologist: J. G. Norwoop. 
Heads of Sub-corps: J. Evans, B. F. Saumarp, B. C. Macy, C. WuittLesey, A. 
Litton, R. Owen. 
Sub-assistants: G. WarreEN, H. Prartren, F. B. Mrex, J. Brat. 
I am, Sir, 
Your obedient Servant, 
DAVID DALE OWEN, 
U. S. Georoeisr. 
