The following passage is adapted from an essay on the history of dendrochronology and American Southwest archaeology.
In 1894, astronomer Andrew Ellicott Douglass traveled to Flagstaff, Arizona, commissioned by Percival Lowell to select a site for a new astronomical observatory. While examining pine timber logs across the high-altitude Colorado Plateau, Douglass noticed that the varying widths of annual growth rings in Pinus ponderosa mirrored regional precipitation patterns. By 1904, Douglass began systematically comparing cross-sections of fallen ponderosa pines and living trees, hypothesizing that annual ring fluctuations directly reflected sunspot activity and solar cycles.
However, establishing an unbroken chronological sequence required extending his timeline further into the past than living trees allowed. In 1914, Douglass approached archaeologists working at prehistoric Puebloan ruins such as Aztec Ruins and Pueblo Bonito, realizing that structural wooden beams recovered from these ancient dwellings could bridge the historical gap. By matching overlapping ring patterns—a technique termed cross-dating—between wood specimens of unknown age and established master sequences, Douglass hoped to construct a continuous timeline.
By the late 1920s, Douglass had successfully constructed two separate chronologies: a modern sequence anchored to living trees stretching continuously back to 1400 CE, and an unanchored floating sequence of 585 relative years derived from prehistoric Pueblo timbers. The gap between these two sequences remained unbridged until the National Geographic Society's third beam expedition in 1929. On June 22, 1929, researchers uncovered a charred wood specimen labeled HH-39 at an archaeological site near Show Low, Arizona. The specimen's outer growth rings precisely matched the earliest portion of the modern 1400 CE chronology, while its inner growth rings overlapped with the final years of the 585-year floating sequence. This single discovery connected the two chronologies into a master timeline spanning over twelve centuries, immediately establishing calendar dates for over forty major Southwestern ruins.
True or False: According to the passage, the charcoal specimen labeled HH-39 contained outer growth rings that overlapped with the prehistoric floating sequence and inner growth rings that matched the modern chronology anchored to 1400 CE.
Answer: Answer