CONTENTS. 
Introduction 
The average composition of rocks 
Analyses of igneous and crystalline rocks 
Malnes ce: fico aasneiotntaseace ones 
1. Rocks from Aroostook Count: 
2. Miscellaneous rocks 
Take: Supériot région. .s.<cauweekioses Pc ae oe fe eeetda ees 
1. Marquette region, Michigan................---.----- 
2. Crystal Falls district, Michigan...........-.--------- 
3. Keweenaw Point, Michigan.............--.....----- 
4, Menominéé Rivers<<:scesevencseeceey seen se sitage sds 
Sturgeon Falls gabbro.........----------0eseee22e eee eee eee eee 
Lower Quinnesec Falls..............--------------- 
Upper Quinnesec Falls...........-- Eaaie domaemmialae gece 
Schist from the Aragon iron mine.............-.---- 
New Hampshitessio.ecciauaw ve e¢e5 24 644s dbdaloadaishinea sane 
Vermonte ecu tyeseniiese cotter eerie ea aN Ae Ga ita ahs 
1. Rocks of Mount Ascutney........-...0.0200.000020-000 2022s cee eee 
2. Miscellaneous rocks................. ee ee ee eee 
Massachusetts............2...-. b 5 sidage ACNAuarneaea eee REE 
1s Mapmesiai: t6Ck6s.2.ccdseenas-sscc eaewcmmnacaavedese se een 
2. Amp bt Olt sic ene Oaaceanars tasennchsaelnnntnan eles 
3. Miscellaneous rocks.................2---20--20--000- 
Connecticut 40%). 4s se cles vane eeles sae eeestewebecauhy weey< 
Niel Worle. c252 spend itlll sted Oe Old aay toga tele te 
1. Rocks of the Adirondack region..............-.......- 
2. Miscellaneous rocks.................2..2------------ 
IN@W Jersey se )2 5.0212 = cisisgeaeainsui hes cose eb aohapndodete: 
Penns ylVanlasaccccarecieassGasaknce ¢.1taanak Whepelanseeeaas 
Maryland and the District of Columbia....................-.- 
1. Peridotite and pyroxenite.................---....--- 
2. Gabbrovand diorite.25:s60s soci ia da seaaeaetieieieies 
3. Granite and gneiss... 2.2.2 5.2. . cee nessdnuwmienens 
4. Miscellaneous rocks.......-....2--..---+0---00022 00> 
Vifginla esos sec esee eid cen deliy sees sesce7a4 +s aeeeeeGs S 
North Carolina csscceses sececeiass 2 oe5 cco Fe sgaidecels eee 
GEOTR1A Loo siesiesie tetracaine ened Seed SAnate eee Sein eseaases 
Rentiichky 220 i552 Sica waeegscinaiiaee £2 52i4 Sh: eae: 
1. Elliott County dike...................2.-2020.20-5--- 
2. Crittenden County dike..............2.....--.------ 
Tenn Gs8@@ 4 :.5:0s0ctiseie vice see et tatan ey aee Sos kee ae eee eee eae eee 
MissOUMwsdciisk ties aso lisiiene eee es Soe SRE ROS 
