What does Dalal measure to determine the health of a watershed?

According to the earth science reference tables, during which geologic time period were the continents of north america,south america, and africa closest together?

Sarah is making a scale drawing of a painting that is 48inches wide by 120 inches high her paper is 12 inches wide and 24 inches tall she decides to use a scale 1 inches equals 4 inches is this a reasonable scale

Explain the reason for having an equator and a prime meridian. how do these two lines us to navigate our world? describe your opinion in at least two to three sentences.