2 GEOLOGICAL SURVEY OF THE TEERITOEIES. 



As soon as suitable preparatious could be made at Denver, three well- 

 equipped parties were assigned to these areas. Each party consisted of 

 a topographer, an assistant topographer, a geologist, two packers, 

 and a cook. There were usually two or three others attached to each 

 party as general assistants or collectors in natural history. 



There were also three other parties, with very important duties to per- 

 form: First, a party under Mr. James T. Gardner, to carry the primary 

 triangulation over the entire area to be explored, thus connecting and 

 harmonizing the work of the first three parties 5 secondly, the photo- 

 graphic party, under Mr. Jackson, which also passes over the entire 

 field, gathering such information and procuring such views as will be 

 useful to all the other parties and to the public generally ; to this party 

 are also attached one or two naturalists or collectors ; thirdly, the 

 quartermaster's party, which furnishes supplies to all the others. It is 

 very important that the working parties in the respective fields shall 

 lose no time from their proper duties, and, with this systematic arrange- 

 ment, they may work through an entire season without the loss of even 

 a day. During the present season (1874) there will probably be a party, 

 consisting of a topographer and the necessary assistants, under the im- 

 mediate direction of the chief geologist, which will make special studies 

 of some of the more complicated areas already examined during the 

 last year. This will render the final work more complete. 



It will be seen, therefore, that the organization is complete and com- 

 pact, and prepared for the systematic work for which it is intended. It 

 may be enlarged at any time to meet the needs of the Government. 

 The addition of one or more parties at any time does not affect the 

 integrity of the organization. Each one of the parties is complete in 

 itself, and may be sent to any portion of the public domain as the needs 

 of the Department may require. 



The divisions operating in the districts assigned during the season* of 

 1873 were denominated for convenience the First or Middle Park divis- 

 ion, Second or South Park division, and the Third or San Luis division. 

 The Middle Park division was directed by A. E. Marvine, assistant 

 geologist, with G. E. Bechler, topographer, and S. B, Ladd, assistant 

 topographer. E. T. Luce and S. H. Nealy were attached to this division 

 for a portion of the season as general assistants. 



The following interesting abstract has been prepared by Mr. Marvine 

 of the work of his division, which will apply, for the most part, to the 

 others. 



The area surveyed by the Middle Park division of the United States 

 Geological and Geographical Survey of the Territories during the season 

 of 1873 comprised an area of about fifty-six hundred square miles, approx- 

 imately in the form of a rectangular belt, its eastern end resting on the 

 plains near Denver City and stretching westward across the main chain 

 of the Eocky Mountains, including the Middle Park. 



The methods of survey were precisely the same as in the other divis- 



