. Elementary physical geography . Fig. of a rock containing fossils. mark the palaeolithic age, others the neolithic; bronzeimplements mark a higher stage, etc. This does not meanan age in any sense in which years are used, but rathera stage. One of these stages may represent a thousandyears, another several thousand; but each one represents astage different from that which preceded and succeeded. So it is with the geological chronology. We have abso-lutely no basis for division into periods of years ; but we can 220 PHYSICAL GEOGRAPHY. divide the history into stages, each stage
. Elementary physical geography . Fig. of a rock containing fossils. mark the palaeolithic age, others the neolithic; bronzeimplements mark a higher stage, etc. This does not meanan age in any sense in which years are used, but rathera stage. One of these stages may represent a thousandyears, another several thousand; but each one represents astage different from that which preceded and succeeded. So it is with the geological chronology. We have abso-lutely no basis for division into periods of years ; but we can 220 PHYSICAL GEOGRAPHY. divide the history into stages, each stage representing someadvance in the development of life on the globe. For thispurpose, names are used to signify the stages, as is indicatedin the table below, which is a simple one from which the TABLE OF GEOLOGICAL AGES. CENOZOICTIME. Age ofmammals. Quaternary. Man assumes importance, particularly inthe upper part. In the first half the Gla-cial Period prevailed. Tertiary. Mammals develop in remarkable variety,and to great size, w
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