"With the dreary season in which we travelled part of the route; with our minds much more actively employed in forming resources for our preservation from famine"

This quote by Zebulon Pike is describing a tough journey he and his companions had actually carried out. The "dreary season" he discusses likely describes a time of year when the weather condition was especially extreme and the surface was difficult to traverse. This would have made the journey much more tough. The truth that their minds were "actively employed in forming resources for our conservation from starvation" suggests that they were struggling to find enough food to sustain themselves. This might have been because of the absence of resources in the area, or because of the harsh conditions making it tough to hunt or forage. It is clear that the journey was a tough one, and that the group needed to use all their ingenuity and resourcefulness to survive.