Internal. The ultimate sources of variation, the source of new heritable characteristics in populations and species, are due to mutation and recombination in chromosomes, genes, DNA.
Zone AE is the flood insurance rate zone that corresponds with flood depths greater than 3 feet. Mandatory flood insurance purchase requirements apply. Zone AH is the flood insurance rate zone that corresponds to areas of shallow flooding with average depths between 1 and 3 feet.
There are 3 flood zones as defined by the EA; Flood Zone 1, 2 and 3. These areas have been defined following a national scale modelling project for the EA and are regularly updated using recorded flood extents and local detailed modelling.