The Three Economic Sectors. According to the three-sector theory, all economic activity can be classified into one of three sectors: the primary sector, the secondary sector and thetertiary sector.
Answer:
the earth surface is constantly changing from force in nature the daily process of precipitation wind and land moments result in changes to landforms over a long period of time driving forces into rows and volcanoes and earthquakes people also contribute to changes in the appearance of land
Sinkholes are common where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by groundwater circulating through them. As the rock dissolves, spaces and caverns develop underground.
Sinkholes are formed when the land surface above collapses or sinks into the cavities or when surface material is carried downward into the voids. Drought, along with resulting high groundwater withdrawals, can make conditions favorable for sinkholes to form.
