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South of San Jose Costa Rica: On The Farm

Environmental Performance Index

Developed by the Earth Institute and Yale's School of Environment, while widely used by The World Economic Forum, the Environmental Performance Index (EPI, image at right) is the most meaningful set of criteria and system for ranking a countries "green" factor. In 2010, the countries ranking 1st, 2nd and 3rd were Iceland, Switzerland and Costa Rica, respectively. The United States ranked 61st.

Used by policy makers and environmental scientists as a benchmark index, the EPI has two general objectives; quantify leading indicators that affect:

i) environmental health

ii) environmental vitality.

Each objective has multiple indicators. Some examples of indicators for environmental health are adequate sanitation, drinking water, and urban particulates. Indicators for environmental vitality include things like irrigation stress, pesticide regulation, industrial carbon intensity and emissions per capita. To measure a countries EPI, indicator outputs are quantified and reported as metrics. Costa Rica's favorable EPI ranking is certainly due to a national commitment of being carbon neutral and environmentally progressive.

Costa Rica

Over the last three million years, the Central American land bridge has driven biotic exchange between the continents. In part, the unusual biodiversity observed in Costa Rica (topographical map left) has been due to the high frequency of biological migration, between the continents, through environmentally diverse locations.

Given converging plates in the Pacific’s Middle American Trench, just 40 miles west of the coast, volcanic activity has stretched a line from Guatemala to Panama. In Costa Rica, there are more than a hundred volcanoes, five of which are still active. The majority of the volcanism in Costa Rica ended around 5-8 million years ago and much of the region is covered by intrusive basaltic formations from past eruptions (image lower right). The plate subductions are expected to have resulted in metamorphism, but there is reported to be little indication of metamorphic rock as it's thought to be buried. The oldest rocks are around 180 million years old and were found on the western coast of the Nicoya peninsula. These old rocks, called ophiolites, have been identified just north and south of CIRENAS and are result of broken chunks of uplifted ocean floor.

12,000 years ago: Pleistocene ends

Whereas formation of the Isthmus of Panama marks the beginning of the Pleistocene epoch (3 MYA), the receding glaciers some 12,000 years ago mark its end. Just before it’s end, around 15,000 years ago, the glacial lake Hitchcock extended from beyond Hartford to St. Johnsbury VT. Having mapped river deltas that trace their flow into Lake Hitchcock, geologists have charted the lakes shore elevation to 300 feet above sea level (corresponds to the present elevation of Eaglebrook School that lies tucked into the Pocumtuck ridge, just east of DA). 15,000 years ago, Deerfield Academy was under water on what would have been the bottom of the lake, hypothetically shown in upper right image (Little and Sillin). Under 150 feet of icy, muddy, Lake Hitchcock water, the soils of present day Deerfield valley remained that way, underwater, against the backdrop of glaciers, for more than a thousand years.

From a human perspective, by 15,000 years ago hunter-gatherers are thought to have passed over the Bering Land Bridge and had become well settled in North America. As the glacial period continued, humans are thought to have passed from North America across the Isthmus of Panama and ventured into South America.

By 8000 years ago, with glaciers retreating, humans migrated back into the northeast and followed their icy retreat venturing north up into Canada, the Arctic Circle and then Greenland.

Richard Little speculates that glacial retreat (technically post glacial crustal rebound) may account for why the Deerfield River unexpectedly flows north in the rift whereas it’s master, the Connecticut River flows south. The image lower left (Little and Sillin) takes a southerly view through the present day Deerfield valley. Crustal rebound says, as the weight of a glacier compressed land underneath by hundreds of feet, more southerly regions would have had the glacial force removed first, given their northerly retreat. From this reasoning, southerly landscapes would be subject to rebounding before northerly landscapes. Moreover, Deerfield river water entering the rift would flow downhill in a north direction where it’s flow eventually met with the Connecticut River.

And what effect was the isthmus of Panama having on human travels during these corresponding times?

American farmers are thought to have emerged in present day Mexico between 3000-5000 years ago growing first squash, chili, then corn and then beans. These nomadic farmers continued from these regions, into South America.

In terms of cities, the first American ones are thought to have developed along the Gulf of Mexico some 3200 years ago. Of course, this frame of time corresponds to the Trojan War, Hebrews moving through Egypt and the Shang Dynasty in China.