As petroleum exploration becomes more complex, the data upon which it is based become more diverse in character. Maps of all kinds; well information; aerial photographs; geologic publications, books, reports, and descriptions; and specialized services of many sorts are some of the basic data used daily. The geologist working in one area gradually becomes familiar with the sources of this information, but if he must work in many areas and examine new regions, much time is often spent in the mere searching for source material and often much valuable material is not used because it is not found.
The directory which follows arose from the belief of the writers that it would be of service to other geologists and would provide them with a start, at least, toward obtaining necessary information when working in any of the states, provinces, or countries of North America. The aim has been to supply addresses and sources of information, leaving it to the user to develop the details of what material is available, its cost, and its reliability. The type of material which was to be included was arbitrarily limited to that which is more commonly used by petroleum geologists but much of it may be useful to other geologists as well. Furthermore, it does not list geophysical surveying companies, well service companies, well drilling contractors, or similar commercial organizations which supply confidential information or services under contract.
The directory is divided into two parts, a general section comprising material of a general character, or information which applies to the continent, to a whole country, to large areas, or to the field of geology as a whole, and a local section in which the information is listed under states and provinces and in which the data are of local application.
The collaborators, without whose help this compilation could not have been made, are credited at the head of each geographic unit. To each of them, for cordial cooperation, the writers wish to express their appreciation and gratitude.
No doubt there have been omissions of essential sources, and there may also be errors in addresses and names. The writers will welcome any additions or corrections from users of the list, and will save them for possible future revision, should the work be found sufficiently useful to justify another edition.
J. V. HOWELL
A. I. LEVORSEN
May 10, 1946.