2) features of the ocean floor; 3) the concept of sea-floor spreading; and. 4) the nature of the Earth's magnetic field and the fact that it has reversed its polarity many times in the past. The Earth's layers â The Earth is a layered planet consisting of crust, mantle and core (Fig. 1).
Run your sprinklers for 15 minutes. Use a ruler to measure the depth of water in each can. Add all the numbers, and then divide by the number of cans to find the average output. This average number is your sprinkler number. It is the average amount of water your sprinklers apply in 15 minutes.
1 Depending on the weather, itâs generally better to water once a week and provide 1 inch to 1 Â½ inches of water. 2  Time how long it takes to apply one inch of water by placing a flat-bottomed can about 6-feet away from the sprinkler.  Do not mow lawns too short; taller grass requires less water.