John Harris (Jack) Stewart of Menlo Park, an authority on the geology of the Great Basin and Colorado Plateau regions of Colorado, Nevada, New Mexico and Arizona, died March 1. He was 84.
Mr. Stewart was born in Berkeley. He graduated from Berkeley High School and the University of New Mexico with a degree in geology. In 1951, he began his 62-year career with the U.S. Geological Survey. He later obtained a doctorate in geology from Stanford University.
In 1962 he was married to Sally Dwight and they had two children, Ed and William. The family spent many summers in Nevada, where he performed extensive field work.
For his achievements in the field of geology in western North America, Mr. Stewart was granted the Distinguished Service Award by the Department of the Interior in 1994.
In 1990 Mr. Stewart married Joyce Colbath, who survives him. He is also survived by his sons, Ed and William; sister Jill Evenson; stepchildren Mary McCurdy, John Plungy, Elizabeth Ramaley, and Mark Plungy; two grandchildren, and eight step-grandchildren.
Donations in his memory may be made to the Truckee-Donner Land Trust.