Accessibility Even if plenty of water is provided, there may be other limits to its use, such as the time taken for people to travel and queue to collect it. If it takes more than 30 minutes to collect water, the amount they will collect will reduce (see Figure 9.4).
. See also Geologic(al) time scale (below). Geologic(al) time scale: a system of chronologic measurement relating stratigraphy to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth.
About the geologic time scale divisions. The geologic history of the Earth is broken up into hierarchical chunks of time. From largest to smallest, this hierarchy includes eons, eras, periods, epochs, and ages. All of these are displayed in the portion of the geologic time scale shown below. The Phanerozoic Eon represents the time during which the majority of macroscopic organisms â algae, fungi, plants and animals â lived. When first proposed as a division of geologic time, the beginning of the Phanerozoic (542.0 million years ago)* was thought to coincide with the beginning of life.