News Â· 10:18 p.m. Â· July 29, 2012. Celebrity Net Worth recently compiled a list of the 20 richest living rappers. At first we were sure that reading their list was going to make us feel very, very bad about the current state of our checking accounts, but no worries â each of these rappers is so wealthy that it's impossible to put into perspective.
Definition of aquifer for English Language Learners. : a layer of rock or sand that can absorb and hold water.
The boundaries of an aquifer are usually gradational into other aquifers, so that an aquifer can be part of an aquifer system. The top of an unconfined aquifer is the water table. A confined aquifer has at least one aquitard at its top and, if it is stacked with others, an aquitard at its base. figure 1. Click on image for larger view. Figure 1 shows an example of an aquifer system in the lower Portneuf River valley.