1840: Ice age - The book of science

Ice age
Imagination of ice
Ice cycles
Commentary

Ice age

Rock beds and faces of rock show parallel grooves
as though gravel locked in moving blocks of ice had scraped them.
Unstratified beds of rounded gravel lay under topsoil
as though they were produced by the trituration
of sheets of ice moving over the surface.
Rock debris arcs across the ends of valleys
as if they were pushed only so far by glaciers.
Slopes and summits are dotted with erratic rocks
as if they were randomly dropped by retreating ice.
Many people had suggested that the northern hemisphere
had been covered with sheets of ice
but it had not been scientifically established
until Louis Agassiz put aside his work as an ichthyologist
identifying species of fossil fishes
and discussed these things
with Jean de Charpentier and Karl Friedrich Schimper
who had gotten their ideas from local inhabitants—
a woodcutter and a chamois hunter.
Agassiz made several trips to the alps
with Charpentier and Schimper
built a hut on one of the Aar glaciers
made detailed observations of the ice
supporting the theory—
that before the elevation of the Alps
vast sheets of ice extended
from the North Pole southwards
over northern Asia
over North America
and over Europe to the southern slopes of the Jura Mountains.
Agassiz published Etudes sur les glaciers in two volumes
giving no credit to Charpentier or Schimper
and personally convinced the influential geologist William Buckland
that ice once covered Scotland.
Buckland then convinced other scientists.
Thus the idea of the ice age was established.

Imagination of ice

The image of grand and gruesome sheets of ice
covering our steep mountains and green valleys
not once but five times
captures the imagination.
Strange mammals gone extinct—
the mastadon and mammoth,
the glyptodon, a Pleistocene armadillo,
the smilodon, a saber-toothed cat,
the megatherium, a sloth as big as an elephant—
give us a larger and more dangerous world
than the world we think we live in.

Ice cycles

Cycles of thawing and freezing
hang icicles from eaves.
Popsicles, Eskimo pies, and ice cream
are as crude as frozen meat
compared to ice in a bird bath
forming a crystal sheet.

In the northern hemisphere, evidence of the ice age lie all about us, but it took someone with curiosity and imagination to see this because so much has changed since then, and because human hearts and minds are not sympathetic to that larger and more dangerous world. In addition to curiosity and imagination, Louis Agassiz also had the intelligence, passion, and persistence to document the effects sufficiently to convince others.

But there are limits. Agassiz resisted Darwin’s theories of evolution all his life.