| Text Description: |
CG5, CG6, and CG7 are from one 55-75 cm thick tephra layer enclosed in a 1-2 m thick coal bed. CG5 is from the base of the layer, is fine-grained, light gray, laminated, with some ripple marks and soft sediment deformation. CG6 is 40-45 cm from the base. It is the same color as CG5. Lamina and ripple marks are more distinct than for CG5. CG7 was collected at the top of the tephra where some coarser-grained pumice grains were observed in an otherwise very fine-grained matrix. No sedimentary structures were noted. About 40-50% of very fine, altered and unaltered pumice grains and bubblewall shards. A small amount of the glass is brown-colored. Five to 7% well-sorted plagioclase grains, some of which are twinned or have altered glass fringes. Trace amounts of quartz, zircon, hornblende, volcanic rock fragments, and biotite. CG5 is the finest-grained sample with mostly glass. |