Accelerated soil erosion around a Mexican highland lake caused by prehispanic agriculture

Article Abstract:

Analysis of 20 sediment cores from the bottom of Lake Patzcuaro, Michoacan, Mexico indicate that native farming methods in use before the Spanish Conquest of 1521 caused as much erosion as the methods used under Spanish rule. Rates of erosion during the Preclassic/early Classic period 2,500 to 1,200 years before present (BP) and during the Postclassic period 850 to 350 years BP were about as high as after 1521. Returning to indigenous agricultural methods has little chance of reversing environmental decline.

Mexico, Soil erosion, Mexican native peoples, Native Americans (Mexico)

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Correlation between rate of sea-level change and frequency of explosive volcanism in the Mediterranean

Article Abstract:

It is possible to use a statistical approach to link the frequency of explosive activity of Mediterranean volcanoes with the rate of late Quaternary sea-level change. It is not likely that there is a single causal link between the rate of sea-level change and the level of explosive activity. For that reason, it is suggested that a number of local or regional mechanisms play a role. Wider-scale influences may be present through slower-acting stress changes in continental margins and at island arcs.

Methods, Volcanic activity prediction

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Climate change and soil erosion

Article Abstract:

S.L. O'Hara and colleague's suggestion that prehispanic agriculture eroded the land upstream from Mexico's Lake Patzcuaro ignores climatic changes and the displacement of high-pressure cells. Reply: Deposition changes following the introduction of maize were much greater than ever before, indicating that climate was not the decisive factor. Erosion also appeared greatest during wet periods, more consistent with agricultural than natural erosion.

Sedimentation and deposition, Deposition (Geology)

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