What is the nature of the most common type of foundation failure? what are its causes?

most foundation are due to excessive differential settlement - most commonly

when a bidg. occupies a site with 2 or more areas of different type of soil with every diff. load bearing capacities. gross failure of a foundation is extremely rare.

answer:

sequence 1- deletion

                  2- duplication

                  3- insertion

                  4- substitute

                  5- inversion

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".