ABSTRACT This trip follows part of the route taken by E.T. Dumble, R.A.F. Penrose, Jr. (later president of and great benefactor to the Geological Society of America), and R.T. Hill as they surveyed the geology from the vantage point of the Colorado River between Austin and La Grange during the Geological Survey of the State of Texas in April of 1889. This year has particular significance because it is the same year that Penrose joined the Geological Society of America. The river has changed in flow regime, and many outcrops have weathered or been flooded. This trip passes through the primarily Claiborne (middle Eocene) geologic section between Bastrop and Smithville, Texas, and illustrates the difficulties to be faced when retracing historic geological surveys. The group will be using and testing a mobile application developed specifically for this field trip theme.