Supplemental Table 5. Stratigraphic unit descriptions for Trench T8.

Noriega, et al. Stream Channel Offset and Late Holocene Slip Rate of the San Andreas Fault at the Van Matre Ranch Site, Carrizo Plain, California

810 2.5Y 6/4 Pale yellow
Very coarse grained, angular to sub-angular, massive, very well indurated, structureless, thin wedge. Bedrock? Difference between 810 and 820 is that 810 is more indurated. Contains filaments and “worms” of carbonate or gypsum.
820 2.5Y 7/4 Pale yellow
Fine grained to coarse grained, poorly sorted, angular to sub-angular, structureless, moderate to poorly indurated, sandy silt. Overlays a more indurated coarser grained 810 unit. Contains poorly developed caliche rinds.
830 2.5Y 7/3 Pale yellow
Very fine grained, poorly sorted, massive, angular to sub-angular, poorly to moderately indurated, matrix supported, silt. With burrows (2x8cm), colluvium underlays 860. Distinctive difference is the lighter color, which marks the boundary.
840 Very coarse to coarse grained, poorly sorted, moderate to well indurated, angular to sub-rounded, massive gravel. Unit is dense. Underlays younger channel 870. Structureless. Clasts up to 10 cm in diameter. Clast supported. Cuts into 810, 820 and 850. Some clasts are up to 18x14 cm.
850 2.5Y 7/4 Pale yellow
Similar to 880 has more CaCO3. Contains subvertical fabric in pebbles, mineralized fractures and fine-grained sediments (rip-up clasts)
860 2.5Y 6/4
Very fine grained, poorly sorted (up to 8 mm), angular to sub-angular, poorly indurated, medium laminated (average 9cm x 3cm). Brown silt, with burrows (4x14cm). Matrix supported, non-fossiliferous, extensively rooted, soil.
870 main channel 2.5Y 6/3 Light yellowish brown
Angular to sub-angular, moderate to well sorted, highly laminated, cross-bedded silty sand. Contains gravel lenses and sand lenses, thin to medium laminations, clasts up to 10cm, scours into 810, 850 and 820, 830 and 860. Gravel lenses range from 15x8 to 40x10 cm, sand lenses average 30x20, 50x10, lenses consist of several scouring channel events. Highly rooted SE side. Samples T8_8, 11, 3, 2, 9, 1 (a, b), 10 were collected in T_8. Contact with 840 is sharp. Interfingers with 880, 820, 860
880 2.5Y 7/4 Pale yellow
Fine grained, moderately to well sorted, sub-angular to sub-rounded, massive, poorly indurated, medium laminated and heavily bioturbated silt.
890 Massive, well-indurated, angular, poorly sorted gravel.

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