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 coalbearing 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 1801.
• 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 1832.
• 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.