Hubbell Trading Post Cultural Landscape Report

PHYSIOGRAPHIC CONTEXT

The state of Arizona covers 113,956 square miles and is comprised of three distinct physiographic areas. The northern area is made up of the plateau and canyon regions, the central area includes the high mountain ranges that run in a northwest - southeast direction, and the southern area has low level river plains in the eastern portion and the Great Desert traversed by the Gila River in the west. [3] The Navajo land is all part of the Colorado Plateau, an intensely dissected rocky region of elevations that range from 3,500 feet above sea level to more than 10,000 feet. According to Kluckholn and Leighton, "variations in climate are connected more with altitude than with northern or southern positions. Altitude is the principal determinant of temperature and length of growing season, of rainfall and the character of the growing season." [4] They continue by stating that "although most of the Navaho area lies between 5,000 and 7,000 feet — one must, from the standpoint of livelihood, distinguish four types of topography and 3 distinct climates. Topographically there are flat alluvial valleys, broad rolling upland plains, rugged tablelands, and mountains." [5] "In roughly one-half of the total acreage (at lower elevations) a warm, arid "desert" climate prevails; perhaps two-fifths must be assigned to an intermediate "steppe" climate characterizing the middle elevations, the remainder is mountainous, with a cold subhumid climate. None of these situations is really favorable to agricultural production save where irrigation water is available." [6]

Figure 4. Pueblo Colorado Wash just west of Hubbell Trading Post, 1993.

Additional natural constraints associated with agricultural land use include high summer temperatures, sub-zero winter weather, high winds, frequent sand storms, and high evaporation rates. While the recorded annual rainfall may appear average for some years, the "precipitation may have come too early or too late or in the form of snow or sudden downpours." [7] There are also droughts, usually two periods each year (April through June and October through December). There have been extensive droughts for every three to eight years over the past fifty years.

The natural vegetation association for the Ganado area is described as the Colorado Plateau Desert Scrub and it is characterized by pinon pine in the higher moist areas grading downward into a pinon-juniper mix and finally into sagebrush alone. [8] According to Goodman, sagebrush is commonly associated with deep soils while short grasses occur in areas where the shallow soils are predominant and the lower drier elevations contain desert scrub vegetation and drought tolerant grasses including salt bush, greasewood, shade scale, alkali sacaton, and Indian rice grass. [9]

The Navajo lands contain numerous extractive resources including timber, coal, oil, helium, vanadium, uranium, and other minerals. The timber consists of four species which are Ponderosa Pine also known as Western Yellow (Pinus ponderosa), Douglas Fir (Pseudotsuga taxifolia), White Fir (Abies concolor), and Engelmann Spruce (Picea engelmanni). Ninety percent of the timber is Ponderosa Pine. [10] Although these resources have provided the Navajo Nation with a substantial source of income over the past several years, the consequences of extraction have often been highly destructive to and resulted in hazardous conditions within the local environment.