Because they began to trade on ships off the coast.
I don’t know the answer to the question List the ways the age of seafloor rocks can be determined.
The mid-nineteenth century was a tumultuous time in the United States. The contestation over slavery's expansion in the 1850s was characterized by the Compromise of 1850 , the Kansas Nebraska Act (1854), the Dred Scott Decision in 1857 and the formal secession of South Carolina from the union with the bombing of Fort Sumter in 1861. The Civil War (1861-1865) led to the defeat of the Confederacy and the emancipation of over four (4) million enslaved people. The assassination of Abraham Lincoln, the desire of Radical Republicans to incorporate enslaved people into the Republic as citizens served as the catalyst for the 14th Amendment, which gave African Americans citizenship.
In general, citizens have the greatest degree of political participation in Israel out of the countries listed, although it should be noted there is still a great amount of repression there.
The French established colonies in Asia in Vietnam and Cambodia.
Hope this helps :)
