Why were slaves important to the colonial economy?

Marine exptoration of oil uses seismic waves to locate oil in the seabed. what is a negative impact from seismic waves on the aquatic ecosystem of the ocean? a. seismic waves kill microoganisms b. seismic waves disrupts the sand and causes seafloor erosion c. seismic waves have virtually no adverse affects on marine life d. seismic waves damage the sonar that dolphins and whales use to orient themselves underwater

Which group was responsible for determining the borders of african colonies and later countries

What is the main difference between primary and secondary sources? a. primary sources are historical documents, and secondary sources are modern-day documents. b. primary sources are derived from museums and archives, and secondary sources are created by history students and academics. c. primary sources are found in ancient places with a rich history, and secondary sources are found in historical journals and blogs. d. primary sources are created during a particular historical era, and secondary sources are created by studying primary sources.