peat - silty peat from the San Andreas fault zone, formed in a marsh that dried out roughly a century ago - large display specimen

This silty peat was collected from a former marsh along Pallett Creek in the San Andreas fault zone, Los Angeles County, California Peat is formed by partial decomposition of plant material under acidic conditions. With burial and compression, peat forms lignite and eventually bituminous coal.  At Pallett Creek, the peat was formed in a marshy sag pond in the fault zone. Layers of leaves and vegetation fell into the marsh and were subsequently covered with sediment. On average, organic and sedimentary units alternate every 25 years. The vegetation was gradually compressed to form peat, forming a layer cake of silty sediment and peat. The marsh was left high and dry about a century ago when the creek was incised during a flood.  When an earthquake occurred along this segment of the fault, the peat and sediment layers would be broken. Following the earthquake, a new and undisturbed peat layer would be deposited above the broken layers. Radiocarbon dating of broken and undisturbed layers