The porphyry deposits are of an undulating blanket form of considerable areal extent and shallow depth.
"The Economic Aspect of Geology"
C. K. Leith
In Michigan, it has been possible to use certain percentage expectations in the areal location of iron formations within certain series of rocks extending over wide areas.
"The Economic Aspect of Geology"
C. K. Leith
Further complication arises from the large areal extent of the impacts expected from a major earthquake, affecting literally dozens of government entities.
"An Assessment of the Consequences and Preparations for a Catastrophic California Earthquake: Findings and Actions Taken Prepared By Federal Emergency Management Agency"
Various