Confused? Me too!
What that means is that earth history can be subdivided into geological time units like the Quaternary based on some natural break in earth conditions. That break should be one of geological significance and one which is easily recognizable all over the world. In this case that break is the beginnings of the global ice ages at around 2.58 Million years ago and it is best represented by the geological section in San Nicola Italy which is being used as the standard or type section. A type section contains a continuous sequence of rock / sediment spanning the break. The base of the new geological time unit can thus be clearly highlighted in the rock record at the type section. Sections marking the beginnings of the ice age are found elsewhere too but it may be exceptionally well preserved at the type section.