What was the name of the barrier at the Appalachian Mountains?

The Appalachian Mountains,[a] often called the Appalachians, are a system of mountains in eastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. They once reached elevations similar to those of the Alps and the Rocky Mountains before experiencing natural erosion.[4][5] The Appalachian chain is a barrier to east–west travel, as it forms a series of alternating ridgelines and valleys oriented in opposition to most highways and railroads running east–west.

Appalachian chain

Explanation:

i hope this

explanation:

max weber's 3 types of authority. the sociologist and philosopher  max weber  distinguishes  three types of authority—charismatic,  traditional  and legal-rational—each of which corresponds to a brand of  leadership that is operative in contemporary society.

ww1 weapons: tank. tanks were used for the first time in the first world war at the battle of the somme. they were developed to cope with the conditions on the western front. the first tank was called 'little willie' and needed a crew of 3.