James Frederick Jackson (1894-1966) was an amateur geologist who had an association with the National Museum of Wales that lasted for 52 years. He was born in Mold, Flintshire, and worked briefly for the museum from 1914-18. Apart from a spell working for the Isle of Wight Natural History Society from 1924-44 he spent much of his life in a rather impoverished state collecting geological specimens. In 1951, with help from a number of distinguished geological friends, he retired to Charmouth, Dorset, where he spent the rest of his life collecting fossils, bed by bed, from the highly fossiliferous Jurassic rocks that outcrop along the local coast. Throughout his life, through the encouragement and financial assistance of Dr F. J. North, the first Keeper of Geology at the National Museum of Wales, he collected rocks, minerals and especially fossils for the museum. By the time of his death, these had amounted to more than 21,000 specimens of which the 6,000 meticulously collected specimens that make up his last Dorset Coast collections are by far the most important. He was an extremely good field geologist with an excellent eye for finding fossils and was made a Fellow of the Geological Society of London in 1923 in recognition of his work in unravelling the geology of the Junction Bed that occurs on the Dorset Coast.