[Wilford Woodruff, 2nd day after arriving in Salt Lake valley]
Ten men including the Twelve were appointed to go on an exploring expedition. ...
Brs Mathews & Brown returned to camp. Had Crossed the valley in the Narrowest place opposite the camp to the mountain on the west. Found the valley about 15 miles across. Passed over A river [Jordan] 4 miles from camp about 8 rods wide from which we saw sulpher hot springs and ensign Peak. We also had A good view of the salt lake through our glass & many rivers & creek runing through the valley.
[Source: Wilford Woodruff's Journal: 1833-1898 Typescript, Volumes 1-9, Edited by Scott G. Kenney, Signature Books 1993, http://amzn.to/newmormonstudies]