Section 7.39 - Mesa Verde National Park(a) Visiting of cliff dwellings is prohibited except when persons are accompanied by a uniformed National Park Service employee. However, the Superintendent may issue special written permits to persons engaged in scientific investigations authorizing such persons to visit the cliff dwellings without escort. The Superintendent shall approve issuance of a permit provided: (1) That the investigation plan proposed, in purpose and in execution, is compatible with the purposes for which the park was established;(2) That the investigation proposed will not jeopardize the preservation of park resources;(3) That the study undertaken will have demonstrable value to the National Park Service in its management or understanding of park resources; and(4) That the permit applicants are adequately experienced and equipped so as to insure that the objectives of paragraphs (a) (1), (2), and (3) of this section will be obtained.(b) Hiking is permitted only on trails designated for that purpose by the Superintendent by the posting of appropriate signs or by marking on a map which shall be available for inspection by the public at park headquarters and other convenient locations within the park. Persons hiking on the Pictograph Point or Spruce Canyon Trails must register in advance with the Superintendent.(c)Commercial automobiles and buses. The prohibition against the admission of commercial automobiles and buses to Mesa Verde National Park, contained in § 5.4 of this chapter shall be subject to the following exceptions: Motor vehicles operated on an infrequent and nonscheduled tour on which the visit to the park is an incident to such tour, carrying only round trip passengers traveling from the point of origin of the tour, will be accorded admission to the park upon establishing to the satisfaction of the Superintendent that the tour originated from such place and in such manner as not to provide, in effect, a regular and duplicating service conflicting with, or in competition with, the services provided for the public pursuant to contract authorization with the Secretary.24 FR 11049, Dec. 30, 1959, as amended at 37 FR 23334, Nov. 2, 1972