Middle Holocene sea-level rise and highstand at+2 m, central Texas coast

New data suggest a revised picture of middle Holocene sealevel change for t he Texas Gulf of Mexico coast, and suggest reevaluation of coastal evolutio n. First, brackish marsh facies with calibrated radiocarbon ages of 7.7 to 7.8 ka have been recovered from depths of -8.5 to -9 m in a core from the a ncestral Colorado River delta, and are interpreted to represent a sea-level pinning point. Second, a series of ridges along the Copano Bay margin fart her south consist of shelly mud and fine sand with subtidal foram assemblag es, occur at elevations of 1.95 m above the modern intertidal zone, and hav e produced calibrated radiocarbon ages on foram tests of ca, 6.8 to 4.8 ha, These ridges are interpreted to represent relict shallow subtidal to inter tidal spits that provide minimum sea-level positions for the middle Holocen e, and are now emergent because of later sea-level fall, In aggregate, thes e data show rates of sea-level rise during this time period that are very c omparable to, or even lower than, published eustatic rates, and suggest a m iddle Holocene sea-level highstand for this non-uplifting, non-rebounding, and very slowly subsiding part of the North American coastline.