We gratefully acknowledge Nelson H. Darton, who first began to catalog the Geological Survey's Photographic Laboratory's collection about 1900. Many of the subjects currently in use are directly related to his committee's work.

We acknowledge Marjorie E. Dalechek, a former Photographic Librarian, who dedicated 25 years to establishing cataloging, preservation, and customer procedures and without whom this collection probably would not exist.

We gratefully acknowledge the Geological Survey scientists who diligently provided both photographs and captions when they deposited their material with the Library or Photographic Laboratory during the past 100 years.

We thank Nancy Papazian and Frances Steele, Volunteers for Science, for their many hours of word-processing the photo captions from the various albums into our system.

We thank all the senior Geological Survey managers, scientists and others who directly and indirectly supported this project.

This publication was prepared by an agency of the United State Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, expressed, or implied or assumes legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed in this report, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United State Government or any agency thereof. Any view and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

Although all data included in this publication have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and related materials and or the functioning of the software. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of the data, software or related materials.

All photographs on this collection are in the public domain; therefore, no copyright release or permission is needed for the reproduction or transfer of these images to another medium.

Photograph credit for photocopy or photographic reprints should be to both the individual or subject collection named in the identification portion of the caption and to the USGS. Electronically transferred images may be credited simply to this U.S. Geological Survey Digital Data Series (DDS-12).