Before 1900, Henry Clifton Sorby, the "founder of sedimentary petrography", covered many aspects of the study of sedimentary rocks. During the first half of the twentieth century, there followed numerous detailed descriptions of such rocks and actualistic ideas were increasingly introduced. Specialization began between the two World Wars. The use of single grains and their statistical evaluation, especially of heavy minerals, and the investigation of clay minerals, were stimulated by the needs of the oil industry, together with regional descriptions, including facies studies on land and on the sea bottom. Specialization further increased between 1945 and 1968, with an explosion of publications. Ongoing field and laboratory studies, and new concepts such as the origin of turbidites, or diagenesis--especially in carbonate rocks--were treated in much greater detail. Again the oil industry was one of the major driving forces. Since 1968, global aspects gained greater attention, as for example with the Deep-sea Drilling Project. Geophysics contributed to facies and basin analysis. Extraterrestrial factors such as variation in Earth's orbit or bolide impacts, and their indications in sediments, came to be considered important for understanding world climates, and also evolution. Cross-disciplinary and international approaches have become, and continue to be, of growing importance.