Many scientists believe that the land bridge theory explains where the earliest americans found boat-building material. why the ice age delayed migration to south america. how people first migrated to north america. why north america experienced an ice age.

how people first migrated to North America.

Explanation:

The Land bridge is a piece of land(narrow or wide) connecting two separate areas which allows living things such as animals and plants to cross over and dominate new lands. A land bridge usually forms when submerged sea floor areas are exposed above the sea level or during plate tectonics. The Land theory was proposed by Jules Marcou. Some scientists observed the existing similarities in the geographical and zoological terrains in this widely separated areas towards the 19th century. They believed that on the land bridge, a diverse specie of vegetation grew and flourished in response to the variation in elevation and the amount of surface water. The vegetation was uniform similar to the arctic plain vegetation. The Land bridge theory was significant to the early human migration in North America. Many scientists believe that the land bridge theory explains how people first migrated to North America.  During the ice age, there was a lowered sea level thereby exposing dry land between the Asia and America. The Land bridge encouraged the movement of people from Asia to America.

answer; /// i believe that the correct answer is (d)the huang he river valley;

b.

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