Prehistory

 

Beginnings of human civilization

 

 

Ice Ages

 

à Summary and references at: Center for the Study of Carbon Dioxide and Climate Change, “Earth’s Climactic History: The Last 2,000,000 Years

 

 

 

§         Peak: 18,000 ya

§         avg. temp. 18 degrees lower than today

§         heavy snows in Arctic

§         ice sheets move south at about 300 ft./yr.

§         Sea surface temperatures were lower than now (even compared to chilly Maine waters!)

§         Higher wind speeds over the oceans (50-80% increase)

§         Climate is much drier during last ice age

1.      Large sand dunes in Central America and sub-Saharan Africa

§         Glacial limit is marked offshore by Long Island, Martha’s Vineyard, Nantucket, and deposits now underwater on Georges Bank

§         Also less carbon dioxide in the atmosphere, so land plants suffer

§         Ice retreated rapidly in some places

1.      In Michigan, the ice retreated and when it was only 5-10 miles away, forests grew, with trees up to 30 feet high. Then 145 years later, ice melted and flooded the forest

§         Maine Ice Age geology

1.      The sand, gravel, and other unconsolidated sediments that cover much of Maine are largely the product of glaciation.

2.      Under Kennebec River as it crosses Bath-Woolwich, there is marine clay – under sand and gravel -- that was deposited as the glaciers melted c. 12,000 ya

3.      “Shells and shell fragments of marine mollusks were found in some samples of this clay. Under the marine clay, some isolated pockets of sandy glacial till were encountered along the section. Glacial till, which is typically a heterogeneous mixture of sand, silt, clay, and stones, but may be predominantly composed of sand in some cases, was deposited directly by the glacier.”(details)

4.      Weight of the glacier sank the Maine coastline from 17,000-12,000 ya

1.      In Topsham, oceans were 250 feet above present-day sea level

5.      Glaciers carved out spaces, and when land “sprung” up, it locked lakes from ocean

àLake Levels and Climate Change in Maine and Eastern North America during the last 12,000 years” | Maine Geological Survey e-books

6.      Found mammoth, walrus, and seal remains in glacial sediment

§         ocean levels drop about 400 feet as ocean water frozen up in the water

1.      Exposed land bridges -- Bering Strait, Japan and mainland China and Korea

§         forms lakes, changes the paths of rivers, erodes land, and deposits sand, gravel, and rocks along the glaciers' paths

§         Ice Age Animals:

1.      Wooly rhino (11 ft long), cave lion (11.5 ft long), glyptodon (armored armadillo – 10 ft long/5ft tall), mammoth (up to 13ft long), mastadon, Irish elk (10ft tall/antlers 11ft across), saber-toothed cats (such as smilodon, fierce predator at 4-5 ft long) (more)

§         Cave dwellers draw pictures of some of these animals

1.      Oldest yet discovered - northern Italy - between 32,000 and 36,500 years old

1.      images of an animal and a human-like creature.

2.      Cave paintings in France and Spain dating to c. 30,000 years

1.      Cave discovered in France in 2001:

1.      Experts describe a 12-metre-high (40-foot) cave, its walls covered in drawings of mammoths, rhinoceroses, horses, human beings and some strange beasts with long, gaping snouts, which scientists have yet to identify.” (source)

3.      In France c. 15,000 ya, lifelike human faces painted on floor of caves (more), as well as stick figures painted on cave walls that date back 30,000 years

4.      South African engravings of geometrical patterns date back 70,000 years (more)

 

§         dogs first, then sheep, goats, and cattle

§         wheat, barley, then beans

§         About 2,000 people

            Cloth – 7,000 B.C.

            Metalworking – 7,000 B.C.

·        Civilization (Latin, civitas “commonwealth” or “city”)

1.      More complex

2.      More control over nature

3.      Rise in technology

4.      Surplus food à increase in population and trade

5.      Invention of writing

 

à Ancient civilizations, hitherto unknown to scientists, are still being discovered.

 

·        In 2001, it was reported that an unknown civilization in Central Asia (Turkmenistan) using writing over 4,000 years ago.

·        “The ancient society is believed to have herded goats, grown crops and made bronze tools and ceramics, all some 300 years after the pyramids of Egypt were built.”

·        “It is not known what the people of the civilisation called themselves, so researchers have dubbed the society the Bactria Margiana Archaeology Complex (B-Mac), after the ancient Greek names for the two regions it covers.”

·        “Archaeologists have uncovered "monumental structures", including multi-roomed mud brick buildings like apartment complexes.” (more)

·        Speculation: Maybe this civilization influenced China in some way?