ocr: s ERA PERIOD ROCK FOSSILS QUARTERNARS(2 to 3Tillion- sears ago) TERTIARSE 60-million- sears ago) CRETACEOUS SECONDARS (150 million JURASSIC CALCAREOUS sears agos TRIASICT GRISTONE PRIMARY. PALAEOZOICU UPPer COAL= 300 million sears ago) PALAEUZUICIower GRANITE PRECHMBRIAN(41 milliard sears. ag0) GRHNLEE