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Pueblo Bonito Chaco Canyon NHP NM USA
 

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Chaco Canyon: updated photos and recent research
Moloka`i Ctenophora: recent research
Halema`uma`u caldera: additional photos and map, Hawai`i Volcanoes National Park
Moonrise over sandstone pipe and Jurassic Entrada Sandstone, Kodachrome State Park, Utah
School of spottail grunt, Isla Espiritu Santo, Gulf of California
Aquatic plants, Isla San Pedro Martir
, Gulf of California

Recent Research



Tree rings are useful for more than dating. They can also help identify timber source areas, a method called tree-ring sourcing. Recent work indicates that most wood came from the Zuni Mountains before 1020 CE and the Chuska Mountains afterwards. So how did Chaco builders drag 5-m beams 75 km without pack animals and hardly scratch the wood? And once there, how did they lift the heavy beams up to a six-story height?

Diamond, Jared (2016), Archaeology: Sources of Chaco wood. Nature 529, 31-33. http://dx.doi.org/10.1038/nature16864

Guiterman, C. H., Swetnam, T. W. & Dean, J. S. (2015), Eleventh-century shift in timber procurement areas for the great houses of Chaco Canyon. Proc. Natl Acad. Sci. http://dx.doi.org/10.1073/pnas.1514272112

The ancestral Pueblo peoples of the US Southwest left established power centers (like Chaco Canyon, NM) and moved north to the Mesa Verde region in the early 1200s.  Within 100 years Mesa Verde was deserted.  Many hypothesis have been offered over the years, but a growing body of work suggests a combination of political disruption, cultural conflict, resource shortage, violence, and drought.  These are forces very much at work in today's Middle East and Africa, with a similar effect.
Monastersky, R. (2015), The greatest vanishing act in prehistoric America. Nature 527, 26–29. doi:10.1038/527026a

Archaeologists are probing the ocean bottom along the west coast of North America.  This was dry coastline 13,000 years ago when the last glacial maximum was waning and sea level was about 100 meters lower than it is today.  The first Americans were moving in from Asia and scientists hope to find evidence of a coastal route.
Marris, E. (2015), Fishing for the first AmericansNature 525, 176–178. doi:10.1038/525176a
Genetic studies have indicated a common origin of Native American groups from Central and South America.  Some morphological studies have suggested a more complex history.   Here, genome-wide data suggest a more diverse founding population.
Skoglund, P., et al (2015), Genetic evidence for two founding populations of the Americas Nature 525, 104–108.  doi:10.1038/nature14895

Favorable geology and good management helped Rome rise to become the capitol of an empire. Rapid and excessive growth (urban, population, and resource) made the city vulnerable to natural disaster.

de Rita, D., Häuber, C. (2014), The smart city develops on geology: Comparing Rome and Naples. GSA Today 25, 4-9. doi:10.1130/GSATG222A.1






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Updated 30 December 2016