PLSO The Oregon Surveyor May/June 2021

16 The Oregon Surveyor | Vol. 44, No. 3 Featured Article • “Starboard” and “larboard” are naval terms for right and left. Why do you think they used naval terms? • Why did Lewis and Clark name a creek after one of the members of the expedition? From these tables Clark plotted their route onmaps calledfield sheets. Thefield sheets contained a background grid of one-inch squares to aid in plotting. One of these finishedmaps shows Clark’s return route along the Yellowstone River. It covers the portion of the route from “Pompy’s Tower” to the mouth of the Big Horn River in present-day Montana. To- day, “Pompy’s Tower” is called Pompey’s Pillar. It is a large rock that was named by Clark in honor of the child of their Sho- shone guide Sacagawea. You can still see Clark’s signature on this rock, which he carved into the soft sand- stone on July 25, 1806. In recognition of its historic association with Lewis and Clark, Pompey’s Pillar has been designated a national historical landmark. Giving names to unnamed features or places is one of the most important and creative acts of themapmaker. Today this activity is coordinated by the U.S. Board on Geographic Names, located in Wash- ington, D.C. The Board reviews all new names and name changes proposed by organizations or individuals. In 1988, the second grade class of Sioux Valley Elemen- tary School in Peterson, Iowa, proposed the name of “BlueBird Creek” for an un- named stream near their school. This name was approved by the Board and now appears on all maps of that region. Journal Maps The Captains also drew small-scale page- size maps. These were drawn in their daily journals. Some are very detailed and show features that affected river travel, such as falls, narrows, and rapids. Others aremerely sketches of large areas. A num- ber were derived from Indian information. Traders and Indian Maps Lewis and Clark also copied or drewmaps based on information that they received from traders and Indians. During the first half of their trip fromSt. Louis to the Great Falls of the Missouri, the two explorers were guided by traders and their French boatman who had visited this region. The further west that they traveled the more they relied upon Indian maps for geo- graphical information that lay beyond their continued T A Map of Lewis and Clark’s Track, Across the Western Portion of North America From the Mississippi to the Pacific Ocean; By Order of the Executive of the United States, in 1804, 5 & 6. Copied by Samuel Lewis from the Original Drawing of Wm. Clark. Smal. Harrison fct. drew by Wesley Jensen.