Table 1. Stratigraphic Age Codes

ERA			PERIOD	EPOCH	CODE
1 Cenozoic			0 Undivided	0 Undivided	100
			1 Quaternary	0 Undivided	110
				1 Holocene	111
				2 Holocene-Pleistocene	112
				3 Pleistocene	113
				9 Quaternary-Tertiary	119
			2 Tertiary	0 Undivided	120
				1 Pliocene	121
				2 Miocene	122
				3 Oligocene	123
				4 Eocene	124
				5 Paleocene	125
				9 Tertiary-Cretaceous	129
	Cenozoic-Mesozoic					199
2 Mesozoic			0 Undivided	0 Undivided	200
			1 Cretaceous	0 Undivided	210
				1 Late	211
				7 Early	217
				9 Cretaceous-Jurassic	219
			2 Jurassic	0 Undivided	220
				1 Late	221
				4 Middle	224
				7 Early	227
				9 Jurassic-Triassic	229
			3 Triassic	0 Undivided	230
				1 Late	231
				4 Middle	234
				7 Early	237
				9 Triassic-Permian	239
		Mesozoic-Paleozoic					299
3 Paleozoic			0 Undivided	0 Undivided	300
		Upper Paleozoic Lower Paleozoic					301 302
			1 Permian	0 Undivided	310
				1 Late	311
				7 Early	317
				9 Permian-Pennsylvanian	319
			2 Pennsylvanian	0 Undivided	320
				9 Carboniferous	329
			3 Mississippian	0 Undivided	330
				9 Mississippian-Devonian	339
			4 Devonian	0 Undivided	340
				1 Late	341
				4 Middle	344
				7 Early	347
				9 Devonian-Silurian	349
			5 Silurian	0 Undivided	350
				1 Late	351
				7 Early	357
				9 Silurian-Ordovician	359
			6 Ordovician	0 Undivided	360
				1 Late	361
				4 Middle	364
				7 Early	367
				9 Ordovician-Cambrian	369
			7 Cambrian	0 Undivided	370
				1 Late	371
				4 Middle	374
				7 Early	377
				9 Cambrian-Proterozoic	379
		Paleozoic-Proterozoic					399
4 Proterozoic			0 Undivided	0 Undivided	400
			1 Late	0 Undivided	410
			2 Hadrynian	0 Undivided	420
			4 Middle	0 Undivided	440
			5 Helikian	0 Undivided	450
			7 Early	0 Undivided	470
			8 Aphebian	0 Undivided	480
	Proterozoic-Archean					499
5 Archean			0 Undivided	0 Undivided	500
			1 Late	0 Undivided	510
			4 Middle	0 Undivided	540
			7 Early	0 Undivided	570
UNKNOWN					***