As a young boy, he collected artifacts in and around the area where he lived, but he did not participate in his first archaeological excavation until he attended Sacramento Junior College (1932–34).
At that time, there was little interest in local archaeology at Berkeley, so Heizer worked with the only graduate student in the field, Waldo Wedel.
[2] He also participated in fieldwork with Alex Krieger and other scholars in Nevada, receiving financial assistance from Francesca Blackmer Wigg.
He also organized and directed the University of California Archaeological Survey (1948–60), which conducted many major excavations and various field studies around the state and produced 75 volumes in its Reports series.
[1] He had never traveled out of the United States until he went to Tabasco to work at the La Venta site in 1955, examining the Olmec society with his colleague Philip Drucker, who had contacted him about his findings there.
After his death Merriam's family donated all his materials to the Anthropology Department at the University of California at Berkeley where Heizer and Kroeber took over the studies.
[1] Most of Heizer's research was in prehistoric and historic Native American peoples of the western United States, particularly in Nevada and California.
He conducted numerous analyses of preserved materials from the caves in Nevada, particularly fossil feces or coprolites, which helped determine what the human diet consisted of and dietary changes over time.
[1] Heizer also used neuron activation analysis to determine trace elements on samples from his excavations in Mexico, one of the applications of this method.