Which of the following events separate geologic time into eras and periods?

a. the number of earthquakes that occur at that time

b. the appearance and disappearance of groups of organisms

c. the appearance and disappearance of volcanoes

d. the creation of new ocean ridges

Excerpt from w. e. b. du bois jon reese 4 du bois was one of the first male civil rights leaders to recognize the problems of gender discrimination. he was among the first men to understand the unique problems of black women, and to value their contributions. he supported the women's suffrage movement and strove to integrate this mostly white struggle. he encouraged many black female writers, artists, poets, and novelists, featuring their works in his crisis magazine and sometimes providing personal financial assistance to them. the cause was that w. e.b. du bois encouraged many black female writers, artists, poets, and novelists. what was the result? think about cause-and-effect relationships.

Why did einstein write a letter to president roosevelt

Astorage company rents square storage units by the area of the unit. which graph shows the relationship between the area (x) of a storage unit and the length of its side (y)?