Cristina M. Lugo Centeno

Years participated in RESESS: 2011


An Overview

Academic Affiliation: University of Puerto Rico, Mayaguez Campus


Born and raised in the mountains of Puerto Rico, Cristina currently studies at the University of Puerto Rico located in Mayaguez. She has always known that she would study Earth Sciences, but what sealed the deal with Geology was her love for working outdoors. She says, “Exploring an entire world of possibilities…is like creating a story!” Cristina enjoys going to the beach and snorkeling, spending time with her friends and family, and reading.


The Snowmastodon Site: Investigation of the Yellow Brick Road

In October 2010, bones of a juvenile Columbian mammoth were found during the excavation of a small reservoir near the town of Snowmass Village, Colorado. Subsequent excavation efforts led by the Denver Museum of Nature and Science recovered more than 4800 bones from at least 26 different Pleistocene taxa, including mammoths, mastodons, ground sloths, bison, camel, and horse, as well as smaller mammals, reptiles, and birds. At this site, informally called the “Snowmastodon Site”, a yellow-banded silt unit delineates the approximate transition between mastodons (below) and mammoths (above). The unique yellow color suggests that chemical and mineralogical differences between this and adjacent units that are likely related to changes in depositional environments. During the summer of 2011, we collected multiple samples from the yellow- banded silt and adjacent units to physically and chemically characterize the sediments and their depositional context. X-Ray diffraction analysis was performed to examine the mineralogical composition of the samples, energy-dispersive x-ray fluorescence was done to quantify elemental concentrations, and grain size analysis was conducted. Results did not reveal significant differences between the yellow-banded silt and adjacent units. However, the yellowish color of the banded silt suggests that the iron (and possibly manganese) species are oxidized, which implies that its deposition occurred during a period of particularly shallow water depths. Faunal remains, including abundant tiger salamanders, snakes, and rodents, also suggest water depths were especially shallow at this time. Work is ongoing to constrain the age, identify possible sediment sources, and further improve our understanding of these depositional environments.