THE COSTA RICAN FIELD EXPERIENCE AT UTC: 20 YEARS IN THE MAKING

Geology Field Experience (GEOL 4960) at The University of Tennessee at Chattanooga is a 3-hr spring-semester course that culminates with a 10-day field trip. Since 1993, the topic and destination have alternated between the Basin and Range and Colorado Plateau (AZ, CA, NV, UT), and the Central American isthmus (Costa Rica). Region-specific geology, taught by traditional lectures (8 wks), is followed by student-led discussions of specific field-trip topics (4 wks). Evaluation is based on assignments, student-led discussions, midterm and final exams, field notebooks and a final written report.

Our studies of convergent tectonics and the Central American isthmus are enriched by well-documented complexities that occur in Costa Rica. Along this short segment of the Middle America trench, the subducting Cocos plate contains (1) relatively normal ocean crust produced at the East Pacific Rise, (2) rough ocean crust with numerous seamounts produced at the Cocos-Nazca spreading center, and (3) thick ocean crust of the Cocos Ridge produced by the Galapagos plume. Such variations in the subducted plate influenced uplift of the isthmus and are of consequence to virtually all aspects of convergent tectonics (angle of subduction, seismicity, volcanism, crustal and lithospheric structure, tectonic accretion vs. erosion, distributions and compositions of igneous and sedimentary rocks, geomorphology, etc.).

Highlights of the trip have included active volcanoes (Arenal, Irazu, Poas, and Rincon), hot springs, emergent coral reefs (Limon, coseismic uplift of April 22, 1991), exposures of relatively young volcanic rock (lava flows, ignimbrite, tuff, lahar), sedimentary rock (patch reefs, clastic and volcaniclastic sediment, limestone, turbidites), and those of the ocean floor (pillow basalt), flora and fauna of cloud forests (Monteverde), coastal rainforests (Cahuita and Manuel Antonio) and moist tropical forests (Cabo Blanco), crocodiles (Rio Tarcoles), and local culture. On May 13, 2011, participants experienced moderate shaking due to an M 6.0 earthquake.

Being cost-conscious makes the field trip affordable and contributes to the great popularity of the course. Total cost to students is approximately $1,000, including airfare, lodging, meals, park fees, and exit tax. The University pays vehicle rental.