1005:
994:
49:
The age of the
Nectaris basin is somewhat contentious, with the most frequently cited numbers placing it at 3.92 Ga, or more infrequently at 3.85 Ga. Recently, however, it has been suggested that the Nectaris basin could be, in fact, much older and might have formed at ~4.1 Ga. Basin Groups are not
41:
The motivation for creating the Basin Groups subdivisions was to place 30 pre-Nectarian impact basins into 9 relative age groups. The relative age of the first basin in each group is based on crater densities and superposition relationships, whereas the other basins are included based on weaker
97:
exists from the time spanned by the Pre-Nectarian period of the Moon, the Pre-Nectarian has been used as a guide by at least one notable scientific work to subdivide the unofficial terrestrial
374:
73:
187:
D. Stöffler and G. Ryder, D.; Ryder, G. (2001). "Stratigraphy and isotope ages of lunar geologic units: chronological standards for the inner solar system".
367:
337:
289:
360:
262:
71:
1033:
51:
383:
282:
68:
66:
70:
67:
341:
26:
656:
651:
275:
151:
69:
42:
grounds. Basin Group 1 has no official age for its base, and the boundary between Basin Group 9 and the
196:
125:
987:
212:
1004:
785:
749:
309:
230:
R. Korotev; J. Gillis; L. Haskin & B. Jolliff (2002). "On the age of the
Nectaris basin".
879:
754:
723:
520:
204:
1028:
848:
744:
682:
577:
546:
515:
141:
200:
998:
817:
687:
582:
551:
1022:
718:
708:
677:
640:
572:
541:
324:
216:
117:
109:
101:
59:
23:
1009:
993:
940:
790:
713:
104:. In particular, it is sometimes found that the Hadean eon is subdivided into the
935:
804:
780:
625:
420:
146:
105:
55:
930:
890:
833:
733:
630:
504:
404:
352:
208:
945:
895:
869:
828:
775:
620:
596:
477:
467:
456:
319:
113:
43:
905:
900:
864:
764:
697:
666:
561:
530:
491:
441:
415:
391:
340:. These subdivisions represent one proposal that is loosely based on the
919:
859:
609:
446:
430:
245:
W. Harland; R. Armstrong; A. Cox; L. Craig; A. Smith; D. Smith (1990).
90:
955:
838:
472:
298:
98:
30:
94:
54:
lunar geologic maps. Basin Groups 1-9 and the earlier (informal)
46:
period is defined by the formation of the
Nectaris impact basin.
979:
975:
971:
356:
271:
171:
129:
121:
65:
267:
336:
The Hadean does not have any subdivisions recognized by the
16:
9 subdivisions of the lunar Pre-Nectarian geologic period
108:
and Basin Groups 1-9 (which collectively make up the
954:
918:
878:
847:
816:
803:
763:
732:
696:
665:
639:
608:
595:
560:
529:
503:
490:
455:
429:
403:
390:
176:. U.S. Geological Survey Professional Paper 1348.
368:
283:
8:
85:Relationship to Earth's geologic time scale
813:
605:
500:
400:
375:
361:
353:
290:
276:
268:
338:International Commission on Stratigraphy
120:. The first lifeforms (self replicating
50:used as a geologic period on any of the
162:
22:refers to 9 subdivisions of the lunar
128:) may have evolved on earth around 4
58:together make up the totality of the
7:
974:= kiloannum (thousands years ago);
84:
978:= megaannum (millions years ago);
14:
982:= gigaannum (billions years ago).
1003:
992:
77:Millions of years before present
52:United States Geological Survey
29:. It is the second era of the
1:
421:Pleistocene (11.7 ka–2.58 Ma)
249:. Cambridge University Press.
152:Geological time scale (Earth)
173:Geologic History of the Moon
384:Geological history of Earth
1050:
657:Mississippian (323–359 Ma)
652:Pennsylvanian (299–323 Ma)
416:Holocene (present–11.7 ka)
247:A Geologic time scale 1989
969:
941:Paleoarchean (3.2–3.6 Ga)
791:Terreneuvian (521–539 Ma)
333:
305:
142:Hadean eon-related topics
936:Mesoarchean (2.8–3.2 Ga)
781:Miaolingian (497–509 Ma)
626:Guadalupian (260–272 Ma)
478:Paleocene (56.0–66.0 Ma)
468:Oligocene (23.0–33.9 Ma)
342:lunar geologic timescale
931:Neoarchean (2.5–2.8 Ga)
896:Orosirian (1.8–2.05 Ga)
891:Statherian (1.6–1.8 Ga)
834:Cryogenian (635–720 Ma)
724:Llandovery (433–444 Ma)
631:Cisuralian (272–299 Ma)
442:Pliocene (2.59–5.33 Ma)
232:Workshop on Moon Beyond
209:10.1023/A:1011937020193
1034:Lunar geologic periods
901:Rhyacian (2.05–2.3 Ga)
870:Calymmian (1.4–1.6 Ga)
829:Ediacaran (539–635 Ma)
776:Furongian (485–497 Ma)
621:Lopingian (252–260 Ma)
447:Miocene (5.33–23.0 Ma)
906:Siderian (2.3–2.5 Ga)
865:Ectasian (1.2–1.4 Ga)
786:Series 2 (509–521 Ma)
473:Eocene (33.9–56.0 Ma)
170:Don Wilhelms (1987).
946:Eoarchean (3.6–4 Ga)
839:Tonian (720 Ma–1 Ga)
719:Wenlock (427–433 Ma)
709:Pridoli (419–423 Ma)
126:RNA world hypothesis
1001: •
990: •
988:Geologic time scale
750:Middle (458–470 Ma)
714:Ludlow (423–427 Ma)
683:Middle (383–393 Ma)
578:Middle (237–247 Ma)
547:Middle (164–174 Ma)
201:2001SSRv...96....9S
89:Since little or no
999:Geology portal
860:Stenian (1–1.2 Ga)
755:Early (470–485 Ma)
688:Early (393–419 Ma)
583:Early (247–252 Ma)
552:Early (174–201 Ma)
521:Early (100–145 Ma)
516:Late (66.0–100 Ma)
325:Lower Imbrian
1016:
1015:
914:
913:
880:Paleoproterozoic
799:
798:
745:Late (444–458 Ma)
678:Late (359–383 Ma)
591:
590:
573:Late (201–237 Ma)
542:Late (145–164 Ma)
486:
485:
407:(present–2.58 Ma)
395:(present–66.0 Ma)
350:
349:
345:
315:Basin Groups
132:during this era.
78:
1041:
1010:World portal
1008:
1007:
997:
996:
959:
923:
883:
852:
849:Mesoproterozoic
821:
814:
809:
768:
737:
701:
670:
644:
613:
606:
601:
565:
534:
508:
501:
496:
460:
434:
408:
401:
396:
377:
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363:
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285:
278:
269:
263:GeoWhen Database
251:
250:
242:
236:
235:
234:: abstract 3029.
227:
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76:
1049:
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1038:
1019:
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1017:
1012:
1002:
991:
983:
965:
957:
950:
921:
910:
881:
874:
850:
843:
819:
818:Neoproterozoic
808:(539 Ma–2.5 Ga)
807:
806:
805:Proterozoic Eon
795:
766:
759:
735:
728:
699:
692:
668:
661:
642:
635:
611:
599:
598:
587:
563:
556:
532:
525:
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124:molecules, see
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72:
39:
27:geologic period
17:
12:
11:
5:
1047:
1045:
1037:
1036:
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1021:
1020:
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1013:
970:
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966:
963:
961:
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951:
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948:
943:
938:
933:
927:
925:
916:
915:
912:
911:
909:
908:
903:
898:
893:
887:
885:
876:
875:
873:
872:
867:
862:
856:
854:
845:
844:
842:
841:
836:
831:
825:
823:
811:
801:
800:
797:
796:
794:
793:
788:
783:
778:
772:
770:
761:
760:
758:
757:
752:
747:
741:
739:
730:
729:
727:
726:
721:
716:
711:
705:
703:
694:
693:
691:
690:
685:
680:
674:
672:
663:
662:
660:
659:
654:
648:
646:
641:Carboniferous
637:
636:
634:
633:
628:
623:
617:
615:
603:
593:
592:
589:
588:
586:
585:
580:
575:
569:
567:
558:
557:
555:
554:
549:
544:
538:
536:
527:
526:
524:
523:
518:
512:
510:
498:
488:
487:
484:
483:
481:
480:
475:
470:
464:
462:
459:(23.0–66.0 Ma)
453:
452:
450:
449:
444:
438:
436:
433:(2.58–23.0 Ma)
427:
426:
424:
423:
418:
412:
410:
398:
388:
387:
382:
380:
379:
372:
365:
357:
348:
347:
334:
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328:
327:
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306:
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294:
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257:External links
255:
253:
252:
237:
222:
189:Space Sci. Rev
179:
161:
159:
156:
155:
154:
149:
144:
137:
134:
86:
83:
75:
64:
38:
35:
15:
13:
10:
9:
6:
4:
3:
2:
1046:
1035:
1032:
1030:
1027:
1026:
1024:
1011:
1006:
1000:
995:
989:
986:
981:
977:
973:
968:
962:
960:
953:
947:
944:
942:
939:
937:
934:
932:
929:
928:
926:
924:
917:
907:
904:
902:
899:
897:
894:
892:
889:
888:
886:
884:
877:
871:
868:
866:
863:
861:
858:
857:
855:
853:
846:
840:
837:
835:
832:
830:
827:
826:
824:
822:
820:(539 Ma–1 Ga)
815:
812:
810:
802:
792:
789:
787:
784:
782:
779:
777:
774:
773:
771:
769:
762:
756:
753:
751:
748:
746:
743:
742:
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738:
731:
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712:
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695:
689:
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671:
664:
658:
655:
653:
650:
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645:
638:
632:
629:
627:
624:
622:
619:
618:
616:
614:
607:
604:
602:
597:Paleozoic Era
594:
584:
581:
579:
576:
574:
571:
570:
568:
566:
559:
553:
550:
548:
545:
543:
540:
539:
537:
535:
528:
522:
519:
517:
514:
513:
511:
509:
507:(66.0–145 Ma)
502:
499:
497:
495:(66.0–252 Ma)
489:
479:
476:
474:
471:
469:
466:
465:
463:
461:
454:
448:
445:
443:
440:
439:
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428:
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417:
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413:
411:
409:
402:
399:
397:
389:
385:
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371:
366:
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163:
157:
153:
150:
148:
145:
143:
140:
139:
135:
133:
131:
127:
123:
119:
118:Lower Imbrian
115:
111:
110:Pre-Nectarian
107:
103:
100:
96:
92:
82:
63:
61:
60:Pre-Nectarian
57:
53:
47:
45:
36:
34:
32:
28:
25:
24:Pre-Nectarian
21:
984:
920:Archean Eon
882:(1.6–2.5 Ga)
767:(485–539 Ma)
736:(444–485 Ma)
700:(419–444 Ma)
669:(359–419 Ma)
643:(299–359 Ma)
612:(252–299 Ma)
600:(252–539 Ma)
564:(201–252 Ma)
533:(145–201 Ma)
492:Mesozoic Era
392:Cenozoic Era
314:
246:
240:
231:
225:
192:
188:
182:
172:
165:
93:evidence on
88:
80:
48:
40:
20:Basin Groups
19:
18:
956:Hadean Eon
734:Ordovician
505:Cretaceous
405:Quaternary
147:Cryptic era
112:), and the
106:Cryptic era
56:Cryptic era
1023:Categories
958:(4–4.6 Ga)
922:(2.5–4 Ga)
851:(1–1.6 Ga)
457:Paleogene
299:Hadean Eon
158:References
91:geological
37:Definition
985:See also:
765:Cambrian
698:Silurian
667:Devonian
562:Triassic
531:Jurassic
320:Nectarian
217:117660264
114:Nectarian
44:Nectarian
610:Permian
431:Neogene
195:: 9–54.
136:See also
62:period.
310:Cryptic
197:Bibcode
1029:Hadean
964:
215:
99:Hadean
31:Hadean
213:S2CID
95:Earth
116:and
205:doi
130:bya
122:RNA
102:eon
1025::
980:Ga
976:Ma
972:ka
211:.
203:.
193:96
191:.
33:.
376:e
369:t
362:v
344:.
291:e
284:t
277:v
219:.
207::
199::
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.