Coverging and Diverging Plates & Snowball Earth
8.5" x 2"
Center of seaglass framed by speckled brown area of subduction sediment from a Costa Rican plate surrounded by a chattered area of Mid-Atlantic Ridge rock slurry. Rim next to words is Namibian rock that, reportedly, proves glaciation at equator 600 to 700 million years ago. Lavender rim overlaps that rock slurry, which is white.
Says, "A white marble, a Snowball Earth -- glaciers riding over drifting continents and friction forces of diving plates".