Dictionary of National Biography, 1885-1900/Trimmer, Joshua
TRIMMER, JOSHUA (1795–1857), geologist, the eldest son of Joshua Kirkby Trimmer, was born at North Cray in Kent on 11 July 1795. When he was about four years old his parents removed to Brentford, Middlesex, to be near his grandmother, Mrs. Sarah Trimmer [q. v.], the authoress. The child spent much time in her company, and she had great influence in forming his character. From 1806 he was instructed by William Davison, curate of New Brentford, and at the age of nineteen was sent to North Wales to manage a copper-mine for his father. Afterwards he was in charge of a farm in Middlesex, but returned in 1825 to oversee some slate-quarries near Bangor and Carnarvon. As he had been always fond of natural history, these occupations turned his thoughts especially to geology, and during his stay in North Wales he made the important discovery that sands containing marine-fossils of existing species lie under a boulder clay almost on the summit of Moel Tryfaen, fully 1,350 feet above sea level. Quitting Wales about 1840 he was for some time employed upon the geological survey of England, but after that spent the remainder of his life in Kent, residing, at any rate for part of the time, at Faversham.
Trimmer was elected a fellow of the Geological Society in 1832, and in 1841 published a book entitled 'Practical Geology and Mineralogy;' he was also, according to the Royal Society's catalogue, the author of twenty-four papers. These, as might be expected from his interest in agriculture, related chiefly to the more superficial deposits of the earth's crust, in the classification of which he made important advances, distinguishing them into northern drift and warp drift; dividing the former and older into a lower or boulder clay, and an upper sand and gravel; and showing that the more widely distributed warp drift rests on an eroded surface of one of these deposits or of some older rock, and is in immediate connection with the surface soil. Owing to his intimate knowledge of these subjects his advice on questions of drainage, planting, and the more scientific aspects of agriculture was much valued. While engaged in writing a book on the geology of agriculture he died, unmarried, in London on 16 Sept. 1857.[Obituary notice Quart. Jour. Geol. Soc. 1858, vol. xiv. p. xxxii.]