Identify Native American Migration Theories?!?

these current theories: bering land bridge theory, pacific coastal route theory, pacific crossing theory, , atlantic crossing theory, here theories , discussion:

bering land bridge

during great ice age, great ice sheets locked of world's water. sea level dropped as 300 feet. changed shape of coastlines. was, , now, bering strait became dry land. asia , americas connected. exposed sea bottom has been named "beringia."

once in americas, found passage south blocked. ice sheets rockies had merged ones hudson bay region. important part bering land bridge when existed, ice blocked way united states. when ice melted, land bridge disappeared.

the major problem theory there archeological sites found on north america same carbon-14 date. (10,500- 12,500 bce). southern tip of south america has sites dated 1,000 years later. that's quite movement of people. supporters must find explanation how ice retreat , people colonize americas quickly.

another issue rate americas occupied. explanations go "if group of hunters moved 25 miles south in each generation..." mountain ranges, climatic changes , distribution of plant , animals not uniformed. nomadic groups tend stay in familiar lands , exploit resources have learned about. it's later, when group splits or famine threatens move.

pacific coastal route theory

this similar bering land bridge theory. people came across through beringia , settled americas. however, used boats , followed pacific coastline.

recent investigations have shown there small refuges along western coastline. sea faring peoples have migrated south along coast. however, finding campsites requires exploration in deep water. few years ago, there dredging operation. sites selected based on expected coastline of 10,000 plus years ago , on known required camping spot. yielded manmade stone tool.

the clovis toolkit uses toggle shaft system. projectile point hafted short foreshaft. fits socket of longer shaft. such system used in hunting sea mammals.

archeological finds in indonesia , australia, show homo erects did cross significant ocean passages. first australians had cross 60 miles of ocean. suggests humans have had ocean sailing abilities.

the problem theory lack or evidence. "clovis first" group claims oldest dated sites clovis , bering land bridge theory explains them. sites, such cactus hill in virginia have dateable preclovis deposits. however, actual evidence scanty , under debate.

pacific crossing theory,

this theory based on observation oldest human sites appear in south america. south america seemed settled first. monte verde, site in far south of chile dated 16,500 bce. these propertied site in brazil claim of 30,000 bce.

the theory has ocean traveling people making landfall in south america after crossing south pacific. that's cold , barren route, few landmasses.

atlantic crossing theory

this theory based on 2 main points. siberia has no corresponding clovis point culture , there's "x factor" in native american blood groupings.

if clovis had started in americas, traces of similar stone technology should appear in asia. doesn't. closest similar stonework comes spain.

the "x factor" in native american blood present in small percentage of population. found in europeans, not asians.

the theory has hunters following edge of polar ice pack. lived off marine animals , sea life. once in north america spread out.

most likely, there number of waves of immigrants americas. arguments number , route seem change daily.

i need answers asap! please!

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