Saltation just means jumping.
Darwin himself was certain that evolution must proceed the same way that the development of cultivars or animal varieties takes place on a farm – inch by inch, each generation producing offspring just barely different from the previous, until the desired improvements are achieved and then locked in place by the wise farmer. Remember also, that he wrote almost 100 years before Watson, Crick, and Rosalind Franklin. He really had no idea even of the cell, let alone the chromosomes or the intricate strand of DNA, so that Behe has written a book, Darwin’s Black Box, titled on that ignorance and its consequences for Darwin’s theory.
The principal evidence that Darwin hoped would verify his theory was expected to be found in the geologic column. The discovery of the long-term fossil sequence was still fairly new in his day; William Smith had already (50 years before) mapped the underside of England and found distinct coal deposits with different fossils; but the changes from one species to another were abrupt, not gradual. This Darwin attributed to the incompleteness of the fossil record, and he was sure it would be remedied over time.
Well, it was not. The sequence remains the same (or similar) everywhere, and so the evidence for a long history of successive life forms is not in doubt, but no full set of minute transitions from one species to a daughter species has yet turned up.
Meantime, almost immediately after Darwin published Origin of Species, Mendel published papers on inheritance that showed its stability and that it was based on specific inheritance factors. When you cross a tall-vined and a short-vined pea plant, you don’t get a medium-height vine; you get some tall and some short. This was a surprise. Darwin was imagining a mushier inheritance, where everything runs together and changes by imperceptible degrees, like a slow change in ocean temperature. For a long time, Mendel’s disturbing paper was just ignored.
In the end, after 40 years of “forgetfulness,” Mendel’s work was resurrected, however, and the neo-Darwinians faced that inheritance is based on little discrete elements, on specific pieces. The new theory located Darwin’s gradual changes in these little pieces (called genes) and taught random variation in the genes. Neo-Darwinism is thus the incorporation of genes into the Darwinian theory.
But single genes still don’t make a species-change, and the geologic record still doesn’t have the imperceptibly gradual changes that Darwin expected and on which he staked his theory. Gene by gene (or at least very gradual) changes are there, but they don’t lead to new species; new species are there, but they arrive quite suddenly. Eventually, Darwinists (still keeping his name) had to content themselves with facing long periods of no evolutionary activity, punctuated by sudden, species-producing jumps. They called this saltation or “punctuated evolution,” which is an oxymoron because it isn’t evolution (gradual change) when nothing is happening, and it isn’t evolution when something dramatic suddenly happens, either.
What is it?
That’s how we come to chromosomal re-patterning.