Also found in: Dictionary, Thesaurus, Medical, Acronyms, Wikipedia.


McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



(or megachron), in geology, the largest stages in the tectonic history of the earth, lasting many hundreds of millions of years. In 1944 the German geologist H. Stille divided the history of the earth into three megacycles: Protogei, Deuterogei, and Neogei. The first of these corresponds to the early Precambrian (Archean), the second to the Middle Precambrian, and the third to the late Precambrian and the Phanerozoic. The term “Neogei” has become best known.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
* Open-water intervals at the base of megacycles 1 and 3 sharply overlie multistorey sandstones in a way consistent with the rapid flooding events interpreted by Browne and Plint (1994).
The upper limit of the Latest Jurassic to Early Cretaceous Megacycle 3 is an intra-Albian unconformity bounding the base of Late Cretaceous Megacycle 4 (Postrift stage 2; Salas et al., 2001) of the Iberian Chain (Fig.
The radar operated at a frequency of 9,375 [+ or -] 45 megacycles and used a superheterodyne receiver.
It uses frequency modulated radio waves in definite frequency channels of 300 megacycles or higher.
Williams, Thermal voltage converters for accurate voltage measurements to 30 megacycles per second, Cumm.
The intercepted signals from the night-fighter told him it was transmitting on 492 megacycles and Bill Bigoray got the first message off to base.