Robert Thomas Hill, geologist, son of Robert Thomas and Catherine Tannehill (Stout) Hill, Sr., was born at Nashville, Tennessee, on August 11, 1858. He was orphaned during the Civil War at the age of five and raised in the home of his grandmother, where he received strict Methodist discipline. He soon developed the rebellious independence that characterized his life. Hill dropped out of school during the sixth grade, then left home at the age of sixteen to work as a printer's devil for the Comanche Chief, a newspaper owned by his brother in Comanche, Texas, then a wild frontier town. For the succeeding eight years he functioned in every capacity at the Chief and was a cowboy on the Dodge City Trail. In 1878 he established his own newspaper in support of the Greenback party but was forced to abandon it after the fourth issue due to conflicts with the staunchly Democratic Chief, which had provided his equipment. He spent his few hours of recreation collecting rocks and fossils around Comanche, a pursuit that led to his reputation as a "rock boy" and to his career in geology.
From 1882 through 1885 he worked his way through Cornell University, where he received his B.S. degree in geology in 1887. In 1885 he began his career with the United States Geological Survey, then directed by John Wesley Powell. His investigations in Texas resulted in his discovery of Lower Cretaceous strata, which he named the Comanche Series after the town where he had first observed them. Between 1887 and 1903 he mapped the Cretaceous strata in the greater Texas region and subdivided the Lower Cretaceous into groups and formations that have since become standard. He discovered the westerly belt of fracture now known as the Texas Lineament, delineated and named the Balcones fault zone (see BALCONES ESCARPMENT), and defined and named the physiographic provinces of the Texas region. His stratigraphic studies and investigations of underground and artesian waters led to improvements of vast areas of farm and ranch land and served as the foundation for future petroleum exploration. Hill composed over 200 papers, books, and maps. His comprehensive Physical Geography of the Texas Region (1900) was the first systematized geography of Texas, and his atlas of the Austin Quadrangle, which contained a study of the Balcones fault zone, remains the type study of the area. His monographs on the Black and Grand prairies and on the Edwards Plateau are standard references for those areas and classics in Texas geology.
Hill helped instigate two state geological surveys in Texas, one in 1888, for which he worked as a geologist, and the other in 1901, which was the predecessor of the Bureau of Economic Geology. He was an assistant professor at the University of Texas in 1888, and in 1899 he led an expedition down the Big Bend of the Rio Grande. In 1921 he was expert witness for Texas in the Texas-Oklahoma boundary suit (see BOUNDARIES). His testimony, along with those of other specialists, permanently won for Texas some 450,000 acres of river-valley lands and over 90 percent of the oil wells along the Red River.
Hill also conducted reconnaissance work in Central America and the West Indies between 1894 and 1902, which led to several technical and popular books and articles and to his support of Panama as the location for the interoceanic canal rather than the favored route of the day, through Nicaragua. He received international attention as one of the first scientists to study the volcano Pelée on the island of Martinique during its catastrophic eruptive cycle of 1902, and he first described its classic "glowing cloud."
Upon the completion of his work in Texas and the West Indies in 1903, Hill resigned from the United States Geological Survey and pursued independent business interests, chiefly in New York, Nevada, California, Texas, and Mexico. He also mapped the geology of the southern part of California, where he recognized the western extension of the Texas Lineament. In 1931 he returned to Texas permanently as a feature writer for the Dallas Morning News. For the last ten years of his life he translated science into useful and interesting information for the layman and stimulated the interests and pride of Texans in their heritage through his scores of lively news articles. He described a route that Álvar Núñez Cabeza de Vaca might have taken through Texas, based upon geologic and physiographic landmarks that he thought he recognized in the original treatise on the journey.
Hill died on July 28, 1941, in Dallas. He was survived by two daughters, one by his first marriage in 1887 to Jennie Justina Robinson, and one by his second marriage in 1913 to Margaret McDermott. He also married a third time in 1939, when he was eighty-one, but his third wife left him after a week. Justina, the daughter of his first wife, became a distinguished bacteriologist and head of the bacteriology laboratory at Johns Hopkins University Hospital. Hill was awarded honorary doctorates by Baylor University and Southern Methodist University. He was an original fellow of the Geological Society of America and an honorary member of the Texas State Historical Association.