500 मिलियन से 425 मिलियन साल पहले; Conodonts और Ostracods और शैवाल और समुद्री शैवाल

Noun:

ऑर्डोविशियन,

ordovician's Usage Examples:

Besides the plant beds extensive outflows of basic lava rest directly upon the Cambrian and Ordovician strata.

Here the folded Archean rocks are overlaid by Cambrian and Ordovician beds, which still lie for the most part flat and undisturbed.

Little is known of the early geological history of Asia beyond the fact that a large part of the continent was covered by the sea during the Cambrian and Ordovician periods.

The Ordovician and Silurian systems are widely developed, and it is most probable that, with the exception of the Archean continents of Finland and the S, the sea covered the whole of Russia.

This Silurian sea was less extensive than the Ordovician in Victoria; but it appears to have been wider in New South Wales and in Queensland.

Marine Ordovician rocks were deposited along the same general course.

The breaking up of the old Archean foundation block began in Cambrian and Ordovician times.

The higher steppes, as far as they are known, consist of Ordovician and Cambrian rocks, with an average elevation of 1500 to 3000 ft.

Contemporaneous volcanic rocks are associated with the Ordovician beds and with the Rhaetic sandstones in several places.

Cambrian, Ordovician and Silurian beds have been recognized, the Upper Cambrian consisting of a limestone which is very rich in metalliferous ores (especially galena and calamine).

ordovician's Meaning':

from 500 million to 425 million years ago; conodonts and ostracods and algae and seaweeds