PREFACE. 



^T^HE continual demand for some of my papers on the geology of Ne- 

 braska, now out of print, suggested the preparation of this volume. It 

 includes in a revised form the most important of my publications on our 

 geology. The greater part of this work, however, is entirely new, and in- 

 cludes many facts and observations now for the first time made known. I 

 had intended to give a much fuller treatment of the Loess deposits and pe- 

 riod, but the materials have accumulated to such an extent that it was 

 thought best to reserve them for a separate volume. In preparing this work 

 I have always kept in mind the many letters of inquiry continually being re- 

 ceived about the State- such questions as are mott frequently asked of a 

 naturalist about Nebraska. Only a small part of the State has received a de- 

 tailed geological examination, and therefore many material points could 

 barely receive mention. In the sketches of our geological history, I have 

 attempted to give an idea of the chain of events that resulted in the present 

 order of things in Nebraska. My conclusions on many points are very dif- 

 ferent from others, but I have come to them by a careful study of our geol- 

 ogy for fifteen years, with all the means which I could command. Wherever 

 I have used the works of others it is acknowledged in the text. It is possi- 

 ble that there are omissions of this kind, as I may not always have remem- 

 bered whether myself or another first observed a fact or discovered a princi- 

 ple. All such omissions, if any, are unintentional. It was intended to in- 

 clude a new geological map of the State in this work, but I have not been 

 able to satisfy myself about the accuracy of some of the boundaries of geo- 

 logical formations, and therefore postpone its publication till spring. 



I am under obligations to Prof. C. D. Wilber for important suggestions; 

 and to many persons over the State, whom I cannot mention in detail, who 

 have provided me with specimens from their localities. I am also under 

 great obligations to the Burlington & Missouri River Railroad in Nebraska, 

 to the Union Pacific Railroad, to the Atchison & Nebraska Railroad, and to 

 other roads for transportation and other favors. Without the aid thus re- 

 ceived, it would have been impossible to make many of the investigations 

 included in this work. Wherever I have gone in the State I have received 

 all possible help from the people in making geological and other natural his- 

 tory examinations. Hoping that this work will help others to understand, 

 the physical conditions of our State, and stimulate an interest in our natural 

 history, I submit it to the people of Nebraska. 



SAMUEL AUGHEY. 



UNIVERSITY OF NERRASKA, January 1st, 1880. 



101283 



