Barbara Tewksbury Hamilton College Why did Ancient Egyptian civilization develop where it did Presence of the Nile Nile is only transSaharan river Seasonal rainfall in high areas of East Africa plus topography that directs water west and north ID: 715697
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Slide1
Why did Egyptian civilization develop where and when it did?
Barbara Tewksbury, Hamilton CollegeSlide2
Why did Ancient Egyptian civilization develop where it did?
Presence of the Nile
Nile is only trans-Saharan
riverSeasonal rainfall in high areas of East Africa plus topography that directs water west and northNile hasn’t always been there: no Nile from ~1.8-0.8 million yrs agoData from rock record allows us to reconstruct whyModern Nile results from tectonic uplift and tilting of areas in East African Rift starting ~800,000 years agoSlide3
Why did
Ancient Egyptian
civilization
develop where it did?Bedrock geologySoft sedimentary bedrock (yellow) eroded easily into wide floodplainsNavigable Nile for 1000 km N of First Cataract at AswanFertile soil carried downstream by Blue Nile from volcanics (purple) of Ethiopian HighlandsUpper Nubia,
Kerma
, Meroe also in sedimentary
stretchesSlide4
Why did Ancient Egyptian civilization develop when it did?
Climate change
–
sea level rose at end of last Ice Age 18,000 years ago, sea level was 125 m lowerDelta surface high & drySea level rose rapidly until about 8,000 years ago, inundating DeltaSince 8000 years ago deposition of fertile sediments has kept pace with sea level rise –agriculture developedSlide5
Why did Ancient Egyptian civilization develop when it did?
Climate change & sea level rise
Changing environments recorded in cores of Delta sediments
Nile Delta suitable for agriculture only after about 8000 years ago (6000 BCE)Agriculture developed on other major deltas of the world as wellLong-term Nile floodplain fertility tied to continued sea level rise - floodplain has risen ~5 m since 1700 BCESlide6
Why did Ancient Egyptian civilization develop when it did?
Climate change
–
rainfall changes in the Sahara6000-8000 BCE, Sahara was wetter than todayRecorded in types of sediments, fossils of animals and plantsNeolithic people lived across SaharaNile floods “wild”Slide7
Why did Ancient Egyptian civilization develop when it did?
Climate change
–
rainfall changes in the Saharaca. 5000 BCE, sharp decline in rainfall and Neolithic sites in Western DesertAppearance of Neolithic sites in Delta and Nile ValleyClimate change documented in the sediment record of paleolakes in the SaharaSahara became uninhabitable about when Nile Valley & Delta became habitable and farmable
In
less than 2000 years, culture changed from isolated Neolithic settlements to villages to kingdoms to a unified empire stretching for 1000 km from Aswan to the Delta in 3050
BCESlide8
Predicting the future
Geologic record indicates cooler worldwide temperatures (e.g., last Ice Age) correlate with less rainfall in Sahara
Warmer was wetter in Sahara as recently as 6000 BCE
Counterintuitively, geologic record suggests that global warming might “green” the Sahara