A group of trappers led by mountain man Joseph Reddeford Walker may have seen Yosemite Valley in the autumn of 1833.[8] Walker approached a valley rim as he led his party across the Sierra Nevada, but he did not enter it. A member of the group, Zenas Leonard, wrote in his journal that streams from the valley rim dropped "from one lofty precipice to another, until they are exhausted in rain below. Some of these precipices appeared to us to be more than a mile high."[9] The Walker party probably visited either the Tuolumne or Merced Groves of giant sequoia, becoming the first non-indigenous people to see the giant trees,[9] but journals relating to the Walker party were destroyed in 1839, in a print shop fire in Philadelphia.[10]