Ewart was born May 17, 1915 to Augusta and Charles Baldwin, the third of their four children. He was born in a log cabin surrounded by a foot of snow in the foothills of the Blue Mountains south of Pomeroy in southeastern Washington. He graduated from high school in Pomeroy and attended Washington State College, where he received an BS and MS in geology. He worked in his family's saw mill and as a copper miner while attending college. In 1940 he headed to Cornell University in Ithaca New York, where he worked toward his PhD in geology. While at Cornell, chance brought him together with Margaret Maxwell, an Oregon State graduate, whom he had met briefly when both attended a church camp on the Olympic peninsula in 1938. They married in October of 1942 and Ewart received his PHD in geology and Margaret completed her work toward an MS in Home Economics.

They returned to the west in 1943, when Ewart took a job with the State of Oregon Department of Geology mapping the Coos Bay area coal resources to aid the war effort. He came to the University of Oregon in 1947, where he taught a variety of courses related to geology including paleontology and stratigraphy, until he retired in 1980. His usual year included teaching three quarters at the U of O followed by a summer working for the United States Geologic Survey, mapping the stratigraphy of southwestern Oregon. This job involved driving back roads and walking up steam beds, looking for places where the sedimentary rock beds were exposed so that he could record the angle and direction of the beds. Ewart wrote many papers and books, the best known being his Geology of Oregon (1959), which he used as a textbook in some of his classes. Not having had enough of a good thing, he taught geology after retirement from the U of O at Whitman College in Walla Walla for a year and a half. In recognition of his contribution to geology, Ewart was awarded the Outstanding Scientist of 2005 by the Oregon Academy of Sciences.

Ewart and Margaret's passion was travel. They went around the world many times as tourists and also with Ewart working as a professor on college campus afloat ships. One of the things he loved about geology was taking students on field trips. Ewart corresponded with and heard from former students all through his life. His favorite form of travel in later years was taking bus trips throughout the west with the Eugene Obsidian Club, telling fellow riders about the history, geography and geology of the scenes outside the bus windows. He was a good friend with a talent for connecting, listening and remembering. He will be missed. His wife Margaret died in 2002. He is survived by his sons Don (Verna) of Springfield and Neil (Rosemary) of Walnut Creek and his grandsons Alan of San Jose and McKenzie of Springfield.