1. Straddling the late Ordovician period and the early Silurian period, the Andean-Saharan ice age was marked by a mass extinction, the second most severe in Earth's history.

2. At the end of the Ordovician period, 440m years ago, a mass extinction event wiped out almost all corals and fish, and 25% of all families of creatures.

3. At the end of Ordovician Period, a differential elevation occurred in the central Shanganning Basin due to the Caledonian Movement.

4. Benxi water tunnel in the limestone is the Ordovician period under the EC-Hill Group and the EC in the Majiagou group, the role of a rock from development.

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5. The natural geography of the Ordovician period is that: the Hannan paleocontinent and the Bashan Mountain rise at the north, and the wide epicontinental sea basin lies in the south.

6. Five past extinctions: Some event near end of the Ordovician period, 440m years ago, wiped out almost all corals and fish, and 25 % of all families of creatures.

7. The third period of the Paleozoic era, the Silurian follows the Ordovician period and precedes the Devonian.

8. The soluble rocks in this area are the carbonate rock constructions of the Sinian, the Cambrian and the Ordovician period.

9. Due to spreading of Helan and Qinling rift valleys during the Ordovician period, a L-shaped swell belt formed in the western and south- ern parts of the basin.

10. Comprehensive researches have concluded that the Heishan ophiolite was formed in Nanhua Ordovician period and its structural location in Silurian period early Middle Devonian epoch.

11. The generation of hydrocarbons of the Ordovician source is different from that of Mesozoic nd Cenozoic sources since there were on high plants in the Ordovician Period.

12. Many coal mine in our country suffers from the Ordovician period Karst containing water inrush frequently due to the complex geology condition, Water inrush is a serious disaster in coal mining.