Position Alpha is very close to the ELCAP Intersection over El Portal CAThe canyon is Yosemite Valley containing the Merced River. We will pass El Capitan (37° 44.15'N 119° 37.95'W 7569 ft) and Yosemite Falls (37° 45.45'N 119° 35.80'W) both to our left.
The left turn is just before Half Dome (8842 ft) and leads over Mirror Lake. The valley to the right is the Little Yosemite Valley containing the upper portion of the Merced River.
Position Beta is in Tenaya Canyon containing Tenaya Creek.
The lake at 37° 49.64'N 119° 27.95'W is Tenaya Lake
Most of this information is from Microsoft Encarta Interactive Word Atlas 2001 or DeLorme Street Atlas USA 7. Intersection identification from Flight Simulator 2004 Map.
Robert
Near KORF