View Full Document. Ultimate base level for all rivers is sea level - Longitudinal profile: way to show a riverâs overall vertical drop. Shows the elevation of its channel bottom from the headwater areas to its downstream termination (the riverâs mouth).
The population is as diverse as it is large, with some 250 ethnic groups. Nigeria's three largest ethnic groups are: Hausa-Fulani (29 percent of the population), Yoruba (21 percent) and Igbo, or Ibo (18 percent).he population is as diverse as it is large, with some 250 ethnic groups. Nigeria's three largest ethnic groups are: Hausa-Fulani (29 percent of the population), Yoruba (21 percent) and Igbo, or Ibo (18 percent).
The first people of Nigerian ancestry in what is now the modern United States came as slaves from the 17th century onwards. Calabar, Nigeria, became a major point of export of slaves, from Africa to the Americas, during the 17 and 18th centuries. Most slave ships frequenting this port were English.ome Nigerian ethnic groups, such as the Yoruba, and some northern Nigerian ethnic groups, had tribal facial identification marks. These could have assisted a returning slave in relocating his or her ethnic group, but few slaves escaped the colonies.