Costa Rican Accretionary Prism
I never met Eli A. Silver who is scientifically associated with this sample. I searched and found this: “During February 1994, we carried out twenty ALVIN dives in search of indicators of fluid venting on the Costa Rica prism. As the trench off Costa Rica reaches depths of 4500m, the ALVIN went through a process of refit and Navy clearance to dive to depths of up to 4500m, and our deepest dive reached that depth.”
I’ve had fun asking people who might know, “What is an accretionary prism?” I’ve heard different answers and seen pictures drawn in air. It got me curious about subduction zones and volcanism. Feed your interest with This Dynamic Planet.
The material, when applied thinly on leather-hard clay is plain smooth matte brown. Thickly applied, it contracts as it dries and curls until later, in the firing, it relaxes down and forms tightly bound clumps of glaze that reveal lots about surface tension and clay wall stresses from forming. What I sense while handling it is an association with the terrific pressure of that zone of plates grinding.