William Smith and biostratigraphy Connecting the history of the earth with the history of life.

Smith and some of his fossils

Superposition As Hooke and Steno had seen, the superposition of one formation on top of another is a reliable indicator of age: lower down = older. When fossils appear in the rock, they too can be ordered by the superposition of the rocks they are found in. Hooke seems to have anticipated that this relation might be the basis of a ‘chronology’.

Collectors Fossils at this time are generally treated as curiosities; something for natural historians to take an interest in. Soulavie was one such collector; he ordered marine strata in southern France by whether or not they contained fossils of forms still living today. Oldest strata contain fossils of animals no longer living (ammonites, belemnites)

Ammonite and belemnites

More layers The youngest strata contain present-day species. The intermediate strata contain both extinct and modern species. Cuvier and Brogniart refined this work in the Paris basin. (1808) Their work made it clear that much finer distinctions could be drawn, with subtly different collections of fossils appearing sequentially.

William Smith Son of a blacksmith, Smith was self-educated, became a surveyor and engineeer, and, along the way, became an important geologist (at a time when being a scientist was really reserved for gentlemen). Mines and canals (before railroads, these were important trade routes allowing much heavier loads of freight to be moved cheaply) were being built all over England; Smith taught himself surveying and went to work as an apprentice to Edward Webb.

Fossils As he traveled about, Smith collected fossils (as he had done in his childhood). Working to survey coalmines and estimate their reserves, he became familiar with the coal- bearing strata and other strata surrounding them. Traveling further and tracing relations, he began to understand the relations between these strata and strata elsewhere in England. While working on a canal, Smith found he could reliably distinguish two very similar strata of rock by the fossils they contained.

Bath and West Joining a local society, Smith became friendly with some other fossil collectors. Smith could tell them what strata their prized fossils had come from, which they found pretty impressive. They persuaded Smith to write his knowledge up, including the sequence of strata and the fossils they contained.

Smith’s table for Bath & region 23 units or strata of rock listed. Thickness, fossils and lithology (types of rock) were noted. The fossils and lithology were generally informally described, using common names and labels of convenience (“Bastard ditto and sundries”). But they represented real evidence: rock units and the different types of fossils that could be found in them.

The first map On becoming unemployed, Smith drew up a map of the area of Bath and a few miles around, marking the different geological formations. What the map shows is bedrock, not soils. This allowed him to trace the contact between different bedrock in different areas, and how the different strata are laid out across the countryside. Smith worked as a consultant for some time, draining water from slopes to prevent landslides, surveying mines, prospecting, and planning canals. Moved to London in 1804, becoming a well-known engineer; saved the springs at Bath by blocking the new channels water had been escaping from (1809).

The Big Map Traveling widely across England on business, Smith formed the idea of preparing a geological map of the entire country. Early plans for the map were made in That plan failed when the map couldn’t be completed in time & the publisher went under. The final product appeared in 1814, fifteen sheets on a scale of one inch to five miles. 23 formations are marked, and the areas where they formed the bedrock were coloured by hand.

1815 Memoir A descriptive account of the formations and the soils of England, including the principle of association between fossils and rock formations. Began work on a volume of pictures of the characteristic fossils for each formation, emerging between 1816 and 1819, but never finished: despite selling off his fossils at a very high price (₤700) Smith went bankrupt and was sent to debtors prison. After his release, he sold off his furniture and books and moved to north England.

More projects, lectures Smith lectured on geology around the country, Began a new project for a ‘geological atlas’, again never completed. Was not a member of the geological society. But received the first award of the Wollaston medal in 1831 in recognition of his work and how useful it had been to geologists. Received a pension from the crown of ₤100 per year in Also awarded an honourary degree in 1835, from Trinity College, Dublin.

Empiricism Both Hutton and Smith emphasized empirical evidence, at the expense of theories. (“unencumbered with theories”) Smith also emphasized practical applications of geological knowledge. And thought of the ordering of fossils as another example of the order/regularity of nature. Smith never did much speculating about just why or how the fossils changed; but he did declare that there had been a series of creations (and destructions) and that there had been a kind of progress over the sequence of fossil flora and fauna.

Providentialism again Smith too saw the earth as created for us, and usefully arranged for us. The different angles of strata allow many different strata to appear in different places, revealing the earth’s history and resources to us. He remained evasive about the age of the earth.