Triassic

Blue green

Permian

Blue

Pennsylvanian

Blue with red

Mississippian

Bluish purple

Devonian

Grayish purple

Silurian

Reddish purple

Ordovician

Subdued red

Cambrian

Reddish brown

Precambrian

(Includes Proterozoic

and Archean)

Olive brown, olive, gray, 

olive blue, reddish olive

Igneous and

volcanic rocks

Red, pink, bright orange

20A0

2010

2000

A000

3A00

5200

AA00

22A0 32A0 43A0 34A0 35A0 33A0 44A0

2210 3210 4310 3410 3510 3310 4410 6530 3420 3520 4630 7740

5420 5520

A100

03A0 04A0 05A0 06A0 07A0 12A0 13A0 14A0 15A0 16A0 17A0 A3A0 A4A0 A5A0 A6A0 A7A0 23A0 24A0 25A0 26A0 27A0 A630 A730 2630 2730 3530 3630 3730

0310

0AA0 01A0 02A0 0330 0430 0530 0630 0730 A430 A530 2330 2430 2530 3430 A440 A540 A640 A740 1450 1550 1650 1750 2450 

0A10

1AA0 AAA0 A1A0 11A0

1A10 AA10 A110

1A20 1120 1220

2130 2230 3340 3130 3230 4340 4440 4540 4640 5340 5440 5540 5640 6340 6440 6540 7440 7540 7640

2240 3350 3460 3330 4350 4450 4550 4650 4750 5350 5450 5550 5650 6350 6450 6550 6650 6750 7450 7550 7650 7750 X450 X550 X650 X750

2250 3350 3460 4360 4460 4560 4660 4760 5360 5460 5560 5660 5760 6460 6560 6660 6760 7460 7560 7660 7760 X460 X560 X660 X760

3370 3470 3570 4370 4470 4570 4670 4770 4X70 5470 5570 5670 5770 6470 6570 6670 6770 6X70 7470 7570 7670 7770 7X70 X470 X570 X670 X770 

33X0 34X0 35X0 36X0 43X0 44X0 45X0 46X0 47X0 4XX0 54X0 55X0 56X0 57X0 64X0 65X0 66X0 67X0 6XX0 5XX0 75X0 76X0 77X0 7XX0

0200 0500 0X00 AX00 1X00 1XA0 1X10 1X20 1X30 1X40 1X50 1X60 1X70 1XX0 0X60 0X70 0XX0 2XA0 2X10 2X20 2X30 2X40 2X50 2X60 2X70 2XX0

0100 0400 0700 A700 1700 AXA0 AX10 AX20 AX30 AX40 AX50 AX60 AX70 AXX0

0A00 0300 0600 A600 1600 0XA0 0X10 0X20 0X30 0X40 0X50 A770 A7X0

0760 0770 07X0 3XA0 3X10 3X20 3X30 3X40 3X50 3X60 3X70 3XX0

X6X0 X7X0 

2A20 2120 2220 3A20 3120 3220 4220 5220 5330 6330 7330

1110 1210

1130 1230 AA20 A120 A220

4A30 4130 4230 4330 4430 4530 5430 6430 7430 7530

2A10 2110 3A10 3110 4210 5320 6320

2AA0 21A0 3AA0 31A0 42A0

0110

0120 0220 0320 0450 0550 0650 0750 1340 1440 1540 1640 3550 3650 3750 A460 A560 A660 A760 1470 1570 1670 1770 

0210 0340 0440 0540 0640 0740 1330 1430 1530 2340 2440 2540 2640 3440 3540 3640 3740 A450 A550 A650 A750 1460 1560 1660 1760 2460 

0410 0510 0610 0710 A2A0 1310 1410 1510 1610 1710 A310 A410 A510 A610 A710 2310 2410 2510 2610 2710 1630 1730

0420 0520 0620 0720 A210 1320 1420 1520 1620 1720 A320 A420 A520 A620 A720 2320 2420 2520 2620 2720 1740

2740

A200 A300 A400 A500 3400 3500 3600 3700 3X00 36A0 37A0 45A0 46A0 47A0 4XA0 57A0 5XA0 5720 5X20 6XA0 7XA0 4X30 5X40 

1200 1300 1400 1500 4600 4700 4X00 6700 6X00 3610 3710 4510 4610 4710 4X10 5710 5X10 5730 5X30 6X10 7X10 4X40

2300 2400 2500 2600 2700 2X00 5700 5X00 7X00 3620 3720 4520 4620 4720 4X20 6X20 7X20 4X60

5X50 

6420 6520 3320 4320 4420 5530 5630 6640 6740

1A00

2A00 2100 2200 3300 5400 5500 5600 7600 7700 X700 XX00 XX10 5410 5510 5610 6410 6510 6610 6710 6630 6730 7610 7710 7630 7730 XX30 XX50 

1100 4300 4400 4500 6500 6600 XXA0 54A0 55A0 56A0 5620 64A0 65A0 66A0 67A0 6620 6720 76A0 77A0 7620 7720 XX20 XX40

4100 4200 7300 7400 7500 5210 5310 6310 7310 7410 7510 X610 X710 X630 X730 X640 X740

3100 3200 5300 6300 6400 X500 X600 52A0 53A0 63A0 73A0 74A0 75A0 7420 7520 X6A0 X7A0 X620 X720

1000 60A0 70A0 X0A0 6010 7010 X010 6A00 6100 6200 XA00 X100 X200 X300 4A10 4110 5A10 5110 6A10 6110 6210 7320 7A10 7110 7210 XA10 X110 

3000 4000 5000 6000 7000 X000 4A00 5A00 5100 7A00 7100 7200 X400 4AA0 41A0 5AA0 51A0 6AA0 61A0 62A0 6220 7AA0 71A0 72A0 XAA0 X1A0 

3010 4010 5010 4030 5030 6030 7030 X030 7050 X050 4A30 4130 4230 5A30 5130 5230 6A30 6130 6230 7A40 7140 7240 

30A0 40A0 50A0 3020 4020 5020 6020 7020 X020 7040 X040 4A20 4120 5A20 5120 6A20 6120 7A20 7120 7220 6A40 6140 6240 7A30 7130 7230 

U.S. Department of the Interior

U.S. Geological Survey

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