The San Pedro River like other rivers can be thought of as a liquid Phoenix that changes greatly over time. The paper below documents major habitat changes along the river during prehistoric and historic times and provides photos at the end showing habitat changes during historic times. Compare figure 23A on page 87 of the paper with the photograph shown below. Figure 23A was taken west of the junction of the Babocomari and San Pedro rivers and shows a view eastward of a topography that gently slopes down to a marshy area without trees. The photo below is taken from the eastern edge of the San Pedro River and looks up (westward) the Babocomari River which is now entrenched and has trees along it. The San Pedro River flows from left to right in the foreground. Notice the sharply eroded banks on the western side of the San Pedro River where it joins the northern edge of the Babocomari River.