Douglass favorite target was the Ponderosa Pine or “Yellow Pine.” The methods he introduced are now generally in use. Douglass is best known for his role in dating the ancient ruins in the Southwest. The focus of Douglass’s studies was not the age of ancient ruins, but the behavior of the sun through time. Many of his publications emphasize this fact, and he reported prominently on reconstructing solar (sunspot) cycles from climate cycles seen in tree growth histories.
