Dirt: The Erosion of Civilizations - Kootenay Local Agricultural Society

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land and birch forest. Following the arrival of agriculture, pollen from
crops and weeds coincide with a threefold increase in the sediment deposition
rate. After the Bronze and Iron Ages, erosion decreased dramatically
for almost two thousand years as native plants regenerated across a largely
abandoned landscape—until erosion accelerated again in the modern era.
Similar cores taken from small lakes in southern Sweden also record the
transition from little preagricultural erosion to much higher rates after
arrival of the plow. One from Lake Bussjösjö shows that forest stabilized
the landscape from 7250 to 750 bc until erosion accelerated following forest
clearing. Erosion increased further under intensified agriculture in the
sixteenth and seventeenth centuries. A core pulled from Havgårdssjön provides
a 5,000-year record of vegetation and erosion. The archaeological
record around the lake has no Bronze or Iron Age artifacts. Lakebed sediments
piled up four to ten times faster after agricultural settlement began
around ad 1100. All across the glaciated terrain of Scandinavia, Scotland,
and Ireland, farmers could not make a living until enough ice-free time
passed to build soil capable of sustaining cultivation.
Put simply, European prehistory involved the gradual migration of agricultural
peoples, followed by accelerated soil erosion, and a subsequent
period of low population density before either Roman or modern times.
Just as in Greece and Rome, the story of central and western Europe is one
of early clearing and farming that caused major erosion before the population
declined, and eventually rebounded.
As the Roman Empire crumbled, the center of its civilization shifted
north. Abandoning Rome as the capital, Diocletian moved his government
to Milan in ad 300. When Theodoric established the Gothic kingdom of
Italy on the ruins of the Roman Empire, he chose Verona as his new capital
in the north. Even so, many of northern Italy’s fields lay fallow for centuries
until an eleventh-century program of land reclamation began
returning them to cultivation. After several centuries of sustained effort,
most of northern Italy’s arable land was again under cultivation, supporting
prosperous medieval cities that nurtured a renaissance of literature and
art.
As northern Italy’s population rebounded, intensive land use increased
silt loads in the region’s rivers enough to attract the attention of Leonardo
da Vinci and revive the Roman art of river engineering and flood control.
Intensive cultivation on hillside farms spread into the Alps, producing similar
results on the Po River as Roman land use had on the Tiber River.
Eventually, after eight centuries of renewed cultivation, even northern
let them eat colonies