250 EXPLORATIONS ACROSS THE GREAT BASIN OF UTAH. 



stratified rocks which have been more or less altered or metamorphosed. In some 

 localities they still exhibit perfectly preserved fossils, in others merely faint traces of 

 organic remains, and in still others their lithological characters show a perfect transi- 

 tion into those of truly metamorphic rocks. Even those which are less altered cannot 

 be sufficiently distinguished from each other, by their lithological characters alone. 

 I therefore have introduced one color for all the rocks which are evidently of Paleozoic 

 age, but which cannot be, with certainty, assigned to any one of the different Paleozoic 

 formations. If, in a range, fossils have been found characteristic of a certain one of 

 these older formations, I have colored the whole range accordingly. In many 

 instances I was doubtful whether I should color rocks as Paleozoic or metamorphic, 

 the transition being so gradual. From the Wahsatch Mountains westward I have 

 marked several deposits with the color adopted for the Post-Pliocene formations, apply- 

 ing the term Post-Pliocene in its widest meaning, that it designates all deposits formed 

 from the close of the Pliocene period to the present day. In that particular district I 

 had thus marked the more solid or regularly stratified deposits, which have been 

 formed posterior to the Tertiary formation, but which I wanted to distinguish from the 

 loose alluvial deposits which have, on the profile, received a distinct color. 



I cannot conclude these remarks without thankfully acknowledging the active 

 interest with which Brig. Gen. A. S. Johnston, commanding Department of Utah, did 

 all in his power to further these surveys. For some valuable specimens in the collec- 

 tion, I am also under obligations to Colonel Crosman of the Quartermaster's Depart- 

 ment, and to the Assistant Surgeons Dr. K. Ryland and Dr. Charles Brewer, the 

 latter of whom communicated some interesting information about the country south of 

 Utah Lake. Last, but not least, I express my gratitude to my commander for his 

 constant desire to facilitate the acquirement of all possible information, and to promote 

 the interests of the survey in general, as well as for the numerous acts of personal kind- 

 ness by winch I have been favored. 



I am, sir, most respectfully, your obedient servant, 



Henry Engelmann, 

 Geologist and Mining 'Engineer. 



Capt. J. H. Simpson, 



Topographical Engineers, U. S. A., in charge of Explorations. 



