Transcript bio2lecture01

DAVE BARRINGTON’S
LECTURES
IN
BIOLOGY 2

Spring, 2002
SEA CLIFF WITH STRATA AT JOGGINS, NOVA SCOTIA
SCALE TREE TRUNK
FOSSIL
IN PLACE IN THE STRATA
AT JOGGINS, NOVA
SCOTIA
DIAMETER OF TRUNK: 60 cm
COAL MEASURE
SEQUENCE AT
POINT ACONI,
CAPE BRETON
ISLAND.
SHALE (MUD
STONE) with
scattered leaf fossils
COAL
SHALE with
rootbearing
Fossils in place
SURFACE OF SCALE TREE STEM WITH DIAMOND-SHAPED
LEAF SCARS
Leaf, Stem, and Cone Fossils of the
Scaletrees
One inch
Rootbearing Fossil of the Scaletrees
One inch
WILLIAM SMITH (1769-1839)
and his map.
Jurassic beds near Lyme Regis on the south coast of Dorset, England, and ammonites from
one of the beds. While studying these beds and others about 1800, William Smith developed
the concept of "guide fossils."
William Smith’s map - inferring a vertical sequence upward from older to younger rocks.
Georges Cuvier (1769-1832) and Alexandre Brongniart (17701847) early recognized the phenomena of restriction of distinctive fossils
to particular zones, formations or series — guide fossils — and applied
this tool in their stratigraphical studies. Moreover, they observed a pattern
or trend in the change from level to level. Of the shells found in the
upper, more recent levels, he states that the "eye of the most expert
naturalist cannot distinguish from those which at present inhabit the
ocean." Forms of life recovered from successively more ancient
strata were observed to become progressively more strange and
"peculiar" (Cuvier 1817:13, 108-109).
Fig. 25.2, p. 468