Environmental planning is but a stage in a journey. At best, planners can aspire to hold the reigns and guide the horses over rough ground. They may leave footprints on the sands of time. Others will then take over. The process is never finished, and land characteristics affect one's ease of travel. From the top of a precipice, vertical travel requires little effort. Making one's way through a mountain, horizontal travel requires great energy. From the heart of a volcano, upward motion is fast but risky. Traversing quicksand can be slow. According to the nature of the land and the intended direction of travel, planners require different information, different tools and different skills.