Earth and Planetary Sciences ETDs

Publication Date



Absolute dated high-resolution records from two speleothems from the southwestern United States (SW USA) are used to constrain the timing and character of the Penultimate Glacial period (NH Glacial-II) and the following glacial termination (T-II) in the northern hemisphere (NH). Speleothems FS-TR3 from Fort Stanton Cave and CaCa-MSC-3 from Carlsbad Caverns National Park reconfirm the close connection between NH Glacial-II climate changes and NH insolation variation. NH Glacial-II maxima observed in the southwestern United States (SW USA) corresponds with Heinrich Event 11 (HE11) and a weak East Asian (EA) monsoon event observed in southeast (SE) China stalagmites SB11 (Cheng et al. 2009) and MSX (Cheng et al. 2006) during a NH insolation minimum ~ 135,000 – 130,000 years ago. Close correspondence between the SE China and SW USA speleothem record reveal a three step termination in association with T-II and the drastic large scale atmospheric responses. NH Glacial cycle-II maximum and termination are far less punctuated by the numerous cold (HE) and warm (Dansgaard-Oeschger DO) events observed in the last glacial record from SW USA speleothems (Asmerom et al. 2010). A hiatus in stalagmite FS-TR3 at 129,997 +/- 359 years is within error of the first termination step in the China speleothem record reported to be 130,200 +/- 100 years. Stalagmite CaCa-MSC-3 top represents the second step at 128,777 +/- 377 years, within error of the second step at 128,951+/- 100 years in the China speleothem record. Second to the large scale climate shifts recorded in FS-TR-3 and CaCa-MSC-3 are shorter superimposed centennial and decal oscillations that are likely the result of shorter climate variation. Spectral analysis of the isotope and elemental time series from our records cluster around some of the previously observed and reconstructed solar productivity and climate oscillations of 78, 80, 181, 200, 232, 355, 400, 421, 568, and 1500 years (Schove 1954, Johnsen 1950, Suess 1980, Xapsos & Burke 2009 and Dansgaard 1970). The measured frequencies in our records suggest climate and solar productivity oscillations similar to those of the Holocene were present through the penultimate glacial period.

Degree Name

Earth and Planetary Sciences

Level of Degree


Department Name

Department of Earth and Planetary Sciences

First Advisor

Asmerom, Yemane

First Committee Member (Chair)

Polyak, Victor

Second Committee Member

Crossey, Laura



Document Type