The Qiiimby and Greenvale 

Cove Formations in 

Western Maine

By ROBERT H. MOENCH

CONTRIBUTIONS TO STRATIGRAPHY

GEOLOGICAL SURVEY BULLETIN 1274-L

-y

Clastic metasedimentary rocks 

A of Late Ordovician(?) age 

are described and newly named
UNITED STATES DEPARTMENT OF THE INTERIOR 

WALTER J. HICKEL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

U.S. GOVERNMENT PRINTING OFFICE, WASHINGTON : 1969

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 - Price 15 cents (paper cover)
CONTENTS

« 

Page

Abstract __ ____-__-_-_---_____-___--_-_-____-_-___---__-__-_____ LI

Introduction. _____________________________________________________ 1

.' Geologic setting. __________________________________________________ 3

Quimby Formation ________________________________________________ 6

Graywacke member ________________________________________ 7

Shale member. ________________________________________________ 10

Greenvale Cove Formation. ________________________________________ 12

Age and origin_______________ _____________________________________ 14

References cited _ _ ________________________________________________ 16

ILLUSTKATIONS

Page 

FIGURE 1. Index map of Maine showing location of report area_________ L2

2. Generalized geologic map of the Rangeley quadrangle._______ 4

3. Stratigraphic columns of the Quimby and Greenvale Cove For- 

. mations. Rangeley area and area of Brimstone Mountain

anticline __ _________________________________________ 8

CONTRIBUTIONS TO STRATIGRAPHY

THE QUIMBY AND GREENVALE COVE FORMATIONS 

IN WESTERN MAINE

By ROBERT H. MOENCH

ABSTRACT

The newly named formations, the Quimby and the Greenvale Cove, in Franklin County, Maine, are composed of clastic metasedimentary rocks of Late 

Ordovician (?) age. The Quimby Formation is about 3,000 feet thick; it conformably overlies the Dixville Formation of Middle Ordovician age. The Quimby consists of two members. The graywacke member is composed of thick-bedded metagraywacke and conglomeratic metagraywacke, a subordinate amount of sulfldic 

metashale, and sparse rhyolitic metavolcanic rocks. The overlying shale member 

is composed of gray or black commonly sulfldic metashale and a subordinate 

amount of metagraywacke. The Quimby Formation is a turbidite-shale sequence 

that was deposited in a euxinic marine environment.

The Greenvale Cove Formation conformably overlies the Quimby and is itself 

conformably overlain by the more coarsely clastic Rangeley Formation of Early 

Silurian (?) age. The Greenvale Cove is 300-600 feet thick. It is composed of 

interlaminated light-gray metasandstone, metasiltstone, and metashale. In the 

southern part of the report area light-colored laminated calc-silicate rocks are 

abundant in the upper part of the formation. Characteristics of the rocks suggest 

that they were deposited in a non-euxinic marine environment which was characterized by active traction currents.

Before the Taconic disturbance, the Quimby and Greenvale Cove Formations 

or their equivalents may have been widespread in New England and southeastern 

Quebec, but if they were, they were removed throughout much of the region by 

the erosion that accompanied the disturbance. Probable age equivalents to the 

Quimby and Greenvale Cove Formations are (1) the Upper Ordovician (?) Sherbrooke Formation, exposed in Quebec about 80 miles northwest of the Rangeley 

area; and (2) part of the Middle Ordovician to Lower Silurian Carys Mills 

Formation, exposed in northern Maine about 180-200 miles northeast of Rangeley.

INTRODUCTION

A lithologically varied section of eugeosynclinal rocks and subordinate amounts of miogeosynclinal rocks of Ordovician, Ordovician (?), 

Silurian (?), and Devonian (?) age has been mapped since 1960 in the 

Rangeley and Phillips quadrangles in western Maine (figs. 1, 2). This 

section is at least 30,000 feet thick, not including the older metasediU
L2 CONTRIBUTIONS TO STRATIGRAPHY

mentary and metavolcanic rocks that are exposed to the northwest 

(Green, 1964; Harwood and Berry, 1967) or the younger rocks to the 

southeast (Osberg and others, 1968). Most of the exposed formations 

in the Eangeley and Phillips quadrangles have been described briefly 

and have been assigned names in a separate report (Osberg and others, 

1968). Upper Ordovician (?) rocks described in that report were not 

named, however, and are named herein the Quimby and Greenvale 

Cove Formations. The distribution of these rocks is shown in figure 2. 

The Quimby and Greenvale Cove Formations correspond to the 

northern argillite of Smith (1923), a mass of dominantly pelitic rocks 

that Smith correctly recognized as being stratigraphically below the 

Eangeley Conglomerate. The Eangeley Conglomerate of Smith (1923) 

has since been redefined as the lower part of the Eangeley Formation 

(Osberg and others, 1968).

100 MILES 

I

FIGTJBE 1. Location of report area (stippled). Quadrangles: 

K, Rangeley; P, Phillips; K, Kennebago Lake; 6, Oquossoc; 

C, Cupsuptic.
L3

GEOLOGIC SETTING

Metasedimentary rocks of the Phillips and Rangeley quadrangles define nearly the full width of the Merrimack synclinorium in western 

Maine (Osberg and others, 1968, fig. 1). Immediately to the northwest 

is the Boundary Mountain anticlinorium. In the area of the anticlinorium, tightly folded Middle Ordovician and older rocks are unconformably overlain toy less deformed Silurian and Devonian rocks 

(Harwood and Berry, 1967). This unconformity, the Taconic, is represented in the Rangeley quadrangle by a conformable contact between 

fine-grained clastic Upper Ordovician (?) rocks and generally more 

coarsely clastic Lower Silurian (?) rocks. All other sedimentary contacts in the area are similarly conformable. Rocks of probable Silurian 

age in the Kangeley and Phillips quadrangles are nearly 15,000 feet 

thick far thicker than rocks of equivalent age to the northwest (Osberg and others, 1968). Moreover, an additional 3,500 feet of Upper 

Ordovician (?) clastic rocks are exposed in the Rangeley quadrangle 

but are apparently absent from the core of the Boundary Mountain 

anticlinorium. These rocks the Quimby and Greenvale Cove Formations lie between the Dixville Formation of Middle Ordovician age 

(Harwood and Berry, 1967) x and the Rangeley Formation of Early 

Silurian(?) age (see p. L14).

Metasedimentary rocks of the Rangeley quadrangle have been tightly 

folded along northeast-trending axes, have been faulted, metamorphosed, intruded 'by large plutons, and have been further deformed 

and metamorphosed at places near the borders of the large plutons. 

The Brimstone Mountain anticline dominates the structure of the 

central part of the Rangeley quadrangle (fig. 2); its axial surface and 

associated phyllitic cleavage and schistosity dip steeply; its axis 

plunges northeast near Long Pond, but is subhorizontal farther southwest (fig. 2). The Quimby and Greenvale Cove Formations define the 

core of the anticline. Here, these rocks are in the staurolite and sillimanite grades of metamorphism (fig. 2); they have been deformed 

by tight minor folds of the Brimstone Mountain anticline and further 

deformed by late generations of slip cleavage, schistosity, and accompanying small nearly recumbent folds. Despite this intense deformation and metamorphism the fine details of sedimentary structural 

features are commonly visible. These features and the sequence of 

lithologies are the bases for the correlation of the Quimby and Greenvale Cove Formations in the Brimstone Mountain anticline with the 

formations near Rangeley Lake (fig. 2).

1 Harwood and Berry (1967) correlated the graptolite-bearing black slates and associated 

greenstone in the southeast corner of the Cupsuptic quadrangle with the Dixville Formation (Green, 1964) and with the Partridge and Ammonoosuc Formations (Billings, 1956). 

Osberg, Moench, and Warner (1968) extended the usage of the name Dixville Formation 

to the rocks of the northwest corner of the Rangeley quadrangle.
CONTRIBUTIONS TO STRATIGRAPHY

70°30'

FIGURE 2. Generalized geologic map of the Rangeley quadrangle. (Map 

explanation shown on facing page.)
QUIMBY AND GREENVALE COVE FORMATIONS IN MAINE L5

EXPLANATION

Granitic and gabbroic rocks

Smalls Falls and Perry Mountain Formations

Rangeley Formation

Greenvale Cove Formation

Quimby Formation

Oqs. shale member

Oqg, grayivaclce member

Dixville Formation

Contact

Fault

Dotted where concealed; queried ivhere conjectural

i f ' f -y 

Anticline Overturned Syncline Overturned 

anticline syncline

Folds 

Showing trace of axial surface

B St

i i Qi i i rsti i i r ^

Metamorphic isograds

B, biotite and chlorite zones undivided 

G, garnet zone 

St, staurolite zone 

Si, sillimanite zone

Type locality of Greenvale Cove Formation and type area of 

Quimby Formation

Additional areas from which data were, obtained for figure 3

324-589 68-
L6 CONTRIBUTIONS TO STRATIGRAPHY

The major tectonic structural features near Kangeley Lake are the 

Haley Pond and South Bog overturned anticlines and the Rangeley 

Lake fault (fig. 2). In addition, an open north-northwest-trending 

syncline has been superposed on the northeast-trending overturned 

folds. This superposition is indicated by the deflected outcrop patterns 

of the graywacke member of the Quimby Formation (fig. 2) and by 

the change in strike of the slaty and phyllitic cleavage ( which is subparallel to the axial surfaces of the overturned folds) from east-northeast on the east side of the troughline to north-northwest on the west 

side. The rocks in the area around Kangeley Lake are generally in the 

chlorite, biotite, and garnet zones of metamorphism, and the rocks have 

a slaty or phyllitic cleavage, as well as younger generations of slip 

cleavage. Relict sedimentary textures and fine details of sedimentary 

structural features, however, are commonly visible.

QUIMBY FORMATION

The Quimby Formation is here named for exposures of metamorphosed graywacke 2 (henceforth called metagraywacke) and slate 

between Quimby Pond and Hunter Cove, which is a narrow embay - 

ment on the north side of Rangeley Lake (fig. 2). Here the formation 

crops out in roadcuts, on low hills, and along Quimby Brook, which 

flows from Quimby Pond to Hunter Cove. These exposures represent 

only the lower part of the formation; equivalent and higher parts of 

the formation crop out elsewhere along the shores of Rangeley Lake, 

on nearby hills, and along tributary brooks. Exposures of the upper 

and lower parts of the formation near Rangeley Lake are designated 

the type area (fig. 2).

Two stratigraphic columns representing the Quimby Formation 

are shown in figure 3. The column representing the Rangeley area was 

compiled principally from data obtained from the type area (fig. 2). 

The column representing the Brimstone Mountain anticline area was 

compiled principally from exposures along Berdeen Stream and from 

two smaller areas farther southwest (fig. 2). In both the Rangeley 

area and the Brimstone Mountain anticline, rocks of the Quimby are

2 In this report the term "graywacke" is used in the broad sense for unsorted sandstone 

composed of angular fragments of feldspar, rock fragments, and quartz set in a detrital 

argillaceous matrix. On figure 96 of Williams, Turner, and Gilbert (1954) the metamorphosed graywacke of the Rangeley area would plot near the boundary between arkosic 

and lithic wackes. Despite thorough recrystallization, at low metamorphic grade in the 

Rangeley area, the characteristic graywacke texture 3s well preserved.. Toward higher 

metamorphic grades, the rocks become equigranular granofels. At all metamorphic grades 

in the area, modal analyses indicate 20-30 percent quartz; 30-45 percent plagioclase 

(albite-oligoclase, commonly untwinned) ; 25-40 percent biotite and (or) chlorite, and 

subordinate amounts of muscovite ; a few percent of staurolite, garnet, calcite, and clinozoisite may be present as well. Clay minerals and potassium feldspar were undoubtedly present 

in the original sediments, but were converted during low-grade metamorphism to chlorite 

and micas.
QUIMBY AND GREENVALE COVE FORMATIONS IN MAINE L7

complexly folded and incompletely exposed. Correlation, therefore, of 

minor stratigraphic zones between the two areas is tenuous.

The Quimby Formation is divisible into (1) a lower graywacke member composed largely of thick-bedded metagray wacke and subordinate 

amounts of interbedded f elsic metavolcanic rocks and metashale and 

(2) an upper shale member composed of thin-bedded metashale and 

subordinate amounts or locally abundant metagraywacke and sparse 

f el sic metavolcanic rocks (fig. 3).

GRAYWACKE MEMBER

The graywacke member of the Quimby Formation is composed of 

interbedded metagraywacke, conglomeratic metagraywacke, and subordinate amounts of metashale and f elsic volcanic rocks. The metagraywacke is medium light gray to light brownish gray; it typically weathers to cream color but locally weathers to rust color. It forms graded 

beds that are typically 6 inches to 5 feet thick, some of which are separated by thin partings or beds of metashale. Commonly the graded 

beds are massive, but locally they show parallel laminations. Crossbedding is rare. In areas of low metamorphic grade, the metagraywacke is composed of angular unsorted fine-grained to very coarse 

grained sand-sized fragments of sodic plagioclase, rock fragments, and 

subordinate amounts of quartz, set in a matrix of chlorite, sericite, and 

local biotite. Some of the larger grains are myrmekitic intergrowths 

of quartz and plagioclase. Calcite and calc-silicate minerals are common, but they rarely form more than 1-2 percent of the rock. Despite 

low-grade metamorphism, the primary graywacke texture is well preserved. A modal analysis (point count) of one specimen of typical 

metagraywacke showed 28 percent quartz, 43 percent plagioclase, 18 

percent biotite, 6 percent chlorite, 2 percent muscovite, 1 percent opaque 

mineral, and about 2 percent sphene, apatite, clinozoisite, and calcite.

Many of the thicker beds of metagraywacke contain abundant thin 

chips of dark-gray slate. Some beds are polymictic metaconglomerate 

that contains abundant granules, pebbles, and small cobbles of metamorphosed shale, siltstone, quartzite, vein quartz, dense white f elsic 

volcanic rocks, and sparse dark-green mafic volcanic rocks. The granules and larger fragments are set in a matrix of typical metagraywacke. 

In all conglomeratic rocks the spaces between the conglomerate fragments are completely filled with metagraywacke, but the proportion of 

matrix to conglomerate fragments is extremely variable. The clasts of 

coarsely crystalline vein quartz are equant and are generally less than 

half an inch across. Most other clasts are thinly tabular with rounded 

to angular edges, and many are extremely elongate. The tabular clasts 

are alined parallel to schistosity; the elongate clasts are alined parallel
L8 CONTRIBUTIONS TO STRATIGRAPHY

RANGELEY AREA

NAME AND. 

THICKNESS DESCRIPTION

Ogu, interlaminated gray metashale ana coarse-grained feldspathic

metasandstone; 100± feet 

Ogm, interlaminated locally calcareous feldspathic metasandstone,

metasiltstone, and subordinate amounts of light-gray metashale;

200± feet

Ogl, interlaminated light-gray metashale and subordinate amounts 

of fine-grained feldspathic metasandstone; sparse laminations 

of metagraywacke; sparse thin beds of calc-silicate rock; 300± feet

Oqss.

:Qqs|

Oqss, sulfide-rich cyclically interbedded dark-gray metashale and 

subordinate amounts of metagraywacke; upper part is metashale 

with sparse metagraywacke; 1-inch beds of metagraywacke form 

25-50 percent of rock in lower part;thin beds of calc-silicate rock and 

sparse felsic metavolcanic rocks present; 400± feet

Oqs, most abundant lithology; medium- to dark-gray metashale 

cyclically interbedded with 25-50 percent metagraywacke in graded 

beds that average 1 inch in thickness; sulfides less abundant than 

in unit Oqss

Oqsg. each zone 100-300 feet thick; metagraywacke, slate-chip 

metagraywacke, and polymictic conglomeratic metagraywacke in 

graded beds that range in thickness from 1 inch to 5 feet; subordinate amounts of gray metashale; large clasts are pebbles of 

metamorphosed sedimentary and volcanic rocks, chert, and vein 

quartz

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Oqg, metagraywacke, slate-chip metagraywacke, and polymictic 

conglomeratic metagraywacke, interbedded with subordinate 

amountsof gray sulfidic metashale and less abundant felsic metavolcanicrock. Metagraywacke typically in graded beds 6 inchesto 

5 feet thick; largest conglomerate clasts are small cobbles of 

metamorphosed sedimentary and volcanic rocks and vein quartz. 

Felsic metavolcanic rocks in beds 3 feet thick or thicker; dense, 

white weathering, rhyolitic

FIGURES, Stratigraphic columns of the Qnimby and Greenvale Cove
QUIMBY AND GREENVALE COVE FORMATIONS IN MAINE L9

AREA OF BRIMSTONE MOUNTAIN ANTICLINE

NAME AND 

THICKNESS

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DESCRIPTION

Ogu, interlaminated noncalcareous feldspathic metasandstone and

metashale; 0-10 feet

Ogm. interlaminated calcareous metasandstone and metasiltstone

metamorphosed to calc-silicate rocks and biotite granofels; 25-200

feet

Ogl, interlaminated light-gray metashale and feldspathic metasandstone; metasandstone beds as much as 1 foot thick; 300± feet

Oqss, sulfide-rich metashale and subordinate metagraywacke; upper 

zone 100-200 feet thick and contains thin-bedded dark-gray sulfidic calc-silicate rocks

Oqs, most abundant lithology; nonsulfidic to slightly sulfidic metashale cyclically interbedded with 25-50 percent metagraywacke;

metagraywacke beds typically 1 inch thick, graded

Oqsg, each zone 100-200 feet thick; metagraywacke in beds 1 inch

to 5 feet thick cyclically interbedded with subordinate amounts

of metashale

^

Oqg, conglomeratic metagraywacke and metagraywacke in beds as 

much as 6 feet thick interbedded with subordijiate amounts of 

metashale; conglomerate' clasts are pebbles of. dense white and 

pale-green metamorphosed sedimentary and volcanic rocks. 

A single-outcrop in West Branch of Swift River; may be part of 

shale member

Formations. Rangeley area and area of Brimstone Mountain anticline.
L10 CONTRIBUTIONS TO STRATIGRAPHY

to one another and define a conspicuous lineation. The felsic volcanic 

rock fragments are composed of fine-grained oligoclase, subordinate 

amounts of quartz, and smaller amounts of muscovite and biotite; a 

few volcanic rocks contain small randomly oriented tabular phenocrysts of oligoclase. The quartzite fragments are composed of 75-90 

percent well-sorted fine-grained quartz, 5-15 percent biotite, and 

minor amounts of oligoclase. These rock types were derived from a 

sedimentary and volcanic terrane.

The metashale interbedded with the metagray wacke is medium-gray 

and dark-gray sulfidic slate and phyllite.

Felsic metavolcanic rock was identified in two outcrops, where it 

forms, respectively, a layer about 3 feet thick and a thicker layer of 

unknown thickness. Such rocks may be more abundant in the graywacke member than is now recognized. The felsic rock is lighter gray 

than the associated metagray wacke; it is dense to fine grained and 

faintly banded. One specimen examined in thin section may be classed 

metarhyolite; it contains about 35 percent quartz, 34 percent potassium 

feldspar, 8 percent altered calcic oligoclase, 17 percent muscovite, 3 

percent biotite, and 3 percent clinozoisite and subordinate accessory 

minerals. The quartz and feldspars are fine grained, equigranular, 

anhedral, and interlocking; the micas are evenly distributed and are 

alined parallel to the phyllitic cleavage. Unlike the associated beds of 

metagray wacke in the same outcrop, the felsic metavolcanic rocks show 

no evidence of an originally clastic texture.

The lower contact of the graywacke member is poorly exposed, but 

it is probably gradational and conformable, because rocks that are 

characteristic of the Quimby and Dixville Formations are present in 

smaller abundances on opposite sides of the contact. The contact is 

placed arbitrarily where the alternating 1- to 3-inch beds of black 

sulfidic metashale and metagray wacke that characterize the upper part 

of the Dixville give way to a much thicker bedded sequence in which 

metagray wacke is predominant.

The graywacke member is about 1,000 feet thick. This approximate 

thickness was interpreted from a north-south structure section between 

the north end of Hunter Cove and the south margin of the pluton to 

the north.

SHALE MEMBER

The dominant rock of the shale member of the Quimby Formation 

is rusty-weathering cyclically interbedded medium-gray to black 

metashale and subordinate amounts of metagraywacke. Although 

bedding thicknesses and the proportions of metashale to metagraywacke are variable, in most outcrops 1- to 3-inch beds of metashale 

alternate with 1-inch beds of metagraywacke. The metashale is vari-
QUIMBY AND GREENVALE COVE FORMATIONS IN MAINE Lll

ably carbonaceous slate, phyllite, or schist. Although aluminum silicate minerals are present in the appropriate metamorphic zones, the 

metashale is somewhat less aluminous than the metashales of younger 

formations. Sulfide minerals, mostly pyrrhotite or pyrite, are nearly 

ubiquitous in the metashale, but their abundance is variable. The 

upper part of the formation in both the Rangeley area and the Brimstone Mountain anticline is particularly sulfide-rich (fig. 3). The beds 

of metagraywacke, typically an inch thick, range locally in thickness 

from paper-thin to 5 feet. Some are lenticular, or pinch and swell along 

strike, but most show little change in thickness where they cross an 

outcrop. Graded bedding and parallel lamination within beds are 

common; cross-lamination is rare.

Distinctive beds of calc-silicate rock that are less than an inch to 

a few inches thick are common in the upper part of the shale member. 

The calc-silicate rock is a dense, brittle, black, and sulfidic rock with 

thin lenses and knots of coarsely intergrown quartz, pyrrhotite, and 

various calc-silicate minerals, such as calcic plagioclase, grossularite, 

actinolite, diopside, and clinozoisite. The dense black rock is probably 

a carbonaceous calcareous metasiltstone. It is typically composed of 

fine-grained calcic plagioclase and smaller amounts of quartz, biotite, 

chlorite, pyrrhotite, and abundant dustlike particles of carbon(?). 

Garnet, clinozoisite, and other calc-silicate minerals may be abundant 

near the coarser-grained knots.

Metagraywacke is more abundant than metashale in two zones in 

both the Rangeley area and the Brimstone Mountain anticline (fig. 3). 

Although these zones seem to occupy about the same stratigraphic positions in the respective areas, data are inadequate to permit them to be 

accurately correlated. In the Rangeley area, metagraywacke of the 

two zones is in graded beds that range in thickness from 1 inch to 

about 5 feet. Many beds contain slate chips. Some beds are conglomeratic, containing tabular and elongate fragments of metamorphosed 

shale, siltstone, quartzite, felsic and mafic volcanic rocks, vein quartz, 

and chert. These fragments are generally confined to the basal few 

inches of the thickest beds, where they are oriented parallel to schistosity or to slaty cleavage, and they are set in a matrix of metagraywacke. The metagraywacke is mineralogically and texturally identical 

with the gray wacke member; quartz is subordinate to plagioclase and 

primary graywacke textures are well preserved. In the Brimstone 

Mountain anticline, an area of more intense metamorphism than the 

Rangeley area, the metagraywacke has an equigranular metamorphic 

texture, but proportions in it of quartz, plagioclase, and micas are the 

same as for the metagraywacke of the Rangeley area.
LI 2 CONTRIBUTIONS TO STRATIGRAPHY

A single bed of probable felsic metavolcanic rock about 10 feet thick 

was found in the upper sulfide-rich zone (fig. 3) in the Eangeley area. 

It is very light gray, dense, and massive and is composed of about 37 

percent quartz, 35 percent plagioclase, 22 percent muscovite, 5 percent biotite, and 1 percent accessory minerals. Viewed in thin section, 

most quartz and plagioclase are fine grained and equigranular, and the 

mica is well foliated and evenly distributed. The rock also has widely 

spaced large anhedral grains of plagioclase and lenticular aggregates 

of quartz and feldspar that are several times as large as the grains of 

the groundmass.

The shale member conformably overlies the graywacke member in a 

gradational zone marked by an upward decrease in the thickness of 

bedding and in the proportion of metagraywacke to metashale. The 

contact is placed where the abundance of metagraywacke becomes less 

than 50 percent and the thickness of bedding decreases to about 1 inch.

The shale member is about 2,000 feet thick. This thickness was interpreted from a structure section that was constructed from data obtained along the east shore of Eangeley Lake.

GREENVALE COVE FORMATION

The Greenvale Cove Formation is named here for exposures of 

light-colored interl animated metashale, metasiltstone, and metasandstone found in roadcuts along State Highway 4 and along the northeast shore of Greenvale Cove, the type locality (fig. 2). The lower 

contact at the type locality is exposed on the lake shore. The upper 

contact is exposed on the hillside about 2,700 feet horizontally eastnortheast of the lower contact. Data for the stratigraphic column of 

the Greenvale Cove in the Rangeley area (fig. 3) were obtained from 

the type locality. Data for the column in the Brimstone Mountain 

anticline were obtained from the areas indicated in figure 2. The 

separate belts of the Greenvale Cove Formation in the northern and 

southern parts of the quadrangle are correlated by lithologic similarity and position in the stratigraphic sequence.

The Greenvale Cove Formation is divisible into three zones in 

both the Eangeley area and the Brimstone Mountain anticline (fig. 3). 

The lower zone, which forms approximately the lower half of the 

formation, is composed of light-gray or pale-greenish-gray or 

brownish-gray metashale interlaminated with about 25-50 percent finegrained metasandstone. In the Eangeley area, the laminations of metasandstone are typically 0.1-0.3 inch thick and range in thickness from 

paper thin to about 0.5 inch, whereas in the Brimstone Mountain 

anticline, laminations of metasandstone tend to be somewhat thicker. 

Beds as much as 1 foot thick are common in the anticline.
QUIMBY AND GREENVALE COVE FORMATIONS IN MAINE LI 3

The middle zone is composed largely of interlaminated metasiltstone and fine-grained metasandstone; metashale is less abundant 

than in the lower zone. In the Brimstone Mountain anticline the 

rocks are interlaminated light-brownish-gray biotite granofels and 

pale-greenish-gray, bluish-gray and white calc-silicate rocks that 

were originally carbonate-cemented clastic quartz-feldspar-rich sediments. In the Kangeley area the clastic rocks of the middle zone are 

generally less calcareous.

The upper zone is thin and locally absent (fig. 3). It is composed 

of equal amounts of interlaminated noncalcareous metasandstone and 

metashale. In the Rangeley area, the metashale of the upper zone is a 

slightly darker gray and the metasandstone is slightly coarser grained 

than the metashale and metasandstone of lower parts of the formation. In the Brimstone Mountain anticline these subtle differences are 

not recognizable, owing to more intense metamorphism.

Most outcrops of the Greenvale Cove Formation are characterized 

by alternating sharply defined laminations of different composition, 

which give the rock a strikingly banded appearance. Graded bedding is 

common, but may be recognizable within only one or two laminations 

of metasandstone at any one outcrop. Some of the thicker laminations 

are faintly internally cross-laminated. The metashale is micaceous 

slate, phyllite, or schist, whereas the metasiltstone and metasandstone 

are poorly foliated micaceous quartz-plagioclase granofels. Except for 

a few laminations of metagraywacke near the base of the formation, 

the metasandstones of the Greenvale Cove are compositionally and 

texturally more mature than those of the Quimby. At low metamorphic 

grades the metasandstones of the Greenvale Cove tend to be better 

sorted, and the ratio of sand-sized clasts to matrix is greater. Modal 

analyses of typical noncalcareous laminations of metasandstone indicate 45-65 percent quartz, 15-30 percent plagioclase (oligoclase), and 

15-30 percent total mica (about 15 percent biotite, and as much as 5 

percent chlorite and 12 percent muscovite in the rocks studied). These 

rocks are compositionally similar to the metasandstones of the overlying Eangeley Formation, but are much richer in quartz than is the 

metagraywacke of the Quimby Formation.

The mineralogy of the calcareous metasiltstone and metasandstone in 

the Brimstone Mountain anticline is varied. The light-brownish-gray 

biotite granofels is composed of about equal amounts of quartz and of 

calcic plagioclase, abundant but smaller amounts of biotite, and minor 

amounts of clinozoisite and sphene; microcline is locally abundant. 

The laminated pale-green, white, and pale-bluish-gray calc-silicate 

rocks are composed largely of quartz, calcic plagioclase, hornblende, 

and diopside in variable proportions; sphene, clinozoisite, and garnet 

are common.
L14 CONTRIBUTIONS TO STRATIGRAPHY

The contact between the Quimby and Greenvale Cove Formation is 

conformable. Where well exposed the contact can be placed within a 

few inches. It is marked by an abrupt gradation from carbonaceous 

sulfidic metashale of uppermost Quimby to lighter gray, less sulfidic, 

more distinctly laminated rocks of the Greenvale Cove. In the Brimstone Mountain anticline, where the upper sulfidic zone of the Quimby 

is thin and only locally exposed, the contact is less definite than it is in 

the Rangeley Lake area.

The contact between the Greenvale Cove Formation and the overlying Rangeley Formation is conformable. Though the sedimentary environment changed abruptly, sedimentation was probably continuous. 

At the type locality the contact is placed at the base of a graded bed of 

coarse-grained feldspathic metasandstone, about 3 feet thick, that 

conforms to bedding in the underlying Greenvale Cove metashale. This 

bed is overlain by a transition zone about 25 feet thick in which thick 

beds of metasandstone alternate with much thinner partings of gray 

metashale. The transition zone is in turn overlain by the main mass of 

basal metasandstone and metaconglomerate of the Rangeley Formation (Osberg and others, 1968). Southward along the limb of the Brimstone Mountain anticline, increasing thicknesses of metashale intervene between the top of the Greenvale Cove and the thick-bedded 

coarse elastics of the Rangeley. This intervening metashale is part of 

the Rangeley Formation. The upper contact of the Greenvale Cove 

Formation in this area is placed where distinctly laminated rock 

abruptly gives way to the generally thicker bedded pelitic rocks of 

the basal part of the Rangeley Formation.

The Greenvale Cove Formation is about 600 feet thick in the Rangeley area and 300-500 feet thick in the Brimstone Mountain anticline. 

These thicknesses were estimated from structure sections that were 

drawn through the areas of best exposure. The formation seems to be 

thinnest near the south boundary of the Rangeley quadrangle.

AGE AND ORIGIN

Approximately 11,500 feet of strata lie between the dated Middle 

Ordovician rocks of the Dixville Formation (Harwood and Berry, 

1967) and the tentatively dated Lower Silurian (?) rocks of the upper 

part of the Rangeley Formation. This thickness includes about 3,000 

feet of Quimby, 500 feet of Greenvale Cove, 4,000 feet of coarse elastics 

in the lower part of the Rangeley Formation (the Rangeley Conglomerate of Smith, 1923), and 4,000 feet of conglomeratic metashales of 

the middle part of the Rangeley Formation. The Early Silurian (?) 

age of the Rangeley Formation is based on the tentative correlation by 

E. L. Boudette and D. S. Harwood of f ossilif erous quartz conglomerate
QUIMBY AND GREENVALE COVE FORMATIONS IN MAINE LI 5

and nearby polymictic conglomerate in the Kennebago Lake quadrangle with the Kangeley Formation a few miles to the south (U.S. 

Geological Survey, 1965, p. A74). The fossils were identified by A. J. 

Boucot as late Llandoverian, C4-C5 . They occur in beds of metamorphosed quartz conglomerate that are interbedded with metasandstone 

and metashale. These rocks are probably equivalent to the interbedded 

locally calcareous quartz metaconglomerate, metasandstone, and metashale of the uppermost 1,000 feet of the Rangeley Formation in the 

Rangeley quadrangle. In turn, the polymictic conglomerate, which actually underlies the fossiliferous rocks, is correlated with the polymictic metaconglomerate of the lowermost 4,000 feet of the Rangeley 

Formation farther south. The author believes, therefore, that only the 

uppermost part of the Rangeley Formation is late Llandoverian 

(C4-C5 ); the lower and middle parts may well be early .or middle 

Llandoverian.

Because of the great thickness of strata between dated rocks, the 

Ordovician-Silurian time boundary is placed tentatively at the most 

conspicuous lithologic change namely, the upper contact of the Greenvale Cove Formation. The Quimby and Greenvale Cove Formations 

are thus considered to be Late Ordovician (?). Further search for 

fossils is recommended in the exposures of uppermost Quimby and 

Greenvale Cove at the north border of the Rangeley quadrangle, about 

5 miles northeast of Rangeley (fig. 2). Low-grade slates of these formations are exposed in that area along Redington Stream, at Flagg 

Dam on the south branch of the Dead River, and along logging roads 

on the north side of the valley. (See U.S. Geol. Survey topographic 

map of Rangeley quadrangle, revised 1949.)

The Quimby Formation is a turbidite-shale sequence that was deposited in a euxinic marine environment. The shaly rocks are gray and 

variably carbonaceous and sulfidic; the interbedded coarser grained 

clastic rocks have characteristics that are commonly attributed to 

turbidity flow deposits, such as poor sorting of immature clastic materials and graded bedding. Turbidity flows bearing large quantities 

of coarse elastics were frequent when the lower graywacke member was 

deposited; they were less frequent and of generally smaller magnitude 

when the upper shale member was deposited. The sandy and .conglomeratic elastics were derived from a sedimentary-volcanic terrane, 

but the whereabouts of this terrane is unknown.

The Greenvale Cove Formation was probably deposited in a 

shallower marine environment than the Quimby; circulation improved 

and traction currents became more important. The rocks are generally 

noncarbonaceous, nonsulfidic, distinctly laminated, locally cross-laminated and are composed of sediments that are better sorted and more
LI 6 CONTRIBUTIONS TO STRATIGRAPHY

mature than those of the Quimby Formation. The fact that part of the 

formation becomes more calcareous toward the south suggests that the 

source area was to the north. Perhaps the Somerset geanticline (Cady, 

1967, p. 64) was beginning to emerge when the Green vale Cove 

Formation was deposited.

In the northern part of the Rangeley quadrangle, the quiet marine 

sedimentary environment of the Greenvale Cove Formation ended 

abruptly with a great influx of coarse clastic sediments. These sediments, now the lower part of the Kangeley Formation, were shed from 

the Somerset geanticline as it was uplifted and deeply eroded during 

the Taconic disturbance. Toward the south, coarse elastics of the 

Rangeley become less abundant and finer grained; they tongue into 

a thick body of gray Kangeley metashale. At the places where this 

metashale overlies the Greenvale Cove Formation, the transition 

represents a subtle change in sedimentary environment. Traction currents gave way to occasional turbidity flows; precipitation of carbonate mineral stopped, and pelitic sediments were deposited in a 

more poorly aerated muddy environment.

Before the Taconic disturbance, the Quimby and Greenvale Cove 

Formations or their equivalents may have been widespread in NCAV 

England and southeastern Quebec, but if they were, they were removed 

throughout much of the region by the erosion that accompanied the 

disturbance. Probable age equivalents of the Quimby and Greenvale 

Cove Formations are (1) the Upper Ordovician (? ) Sherbrooke Formation, exposed in Quebec, about 80 miles northwest of Rangeley (St. 

Julien, 1965) and (2) part of the Middle Ordovician to Lower Silurian 

Carys Mills Formation, exposed in northern Maine about 180-200 miles 

northeast of Rangeley (Pavlides and Berry, 1966; Pavlides, 1966). The 

Carys Mills Formation and the Quimby and Greenvale Cove Formations were probably deposited in the same sedimentary trough. This 

trough apparently continued to subside during the Taconic disturbance 

and received sediments from the adjacent rising areas (Pavlides and 

others, 1968; Osberg and others, 1968). Whether the Sherbrooke 

Formation and the rocks of similar age in Maine once joined across 

the Somerset and Stoke Mountain geanticlines (Cady, 1967) cannot be interpreted from present information.

REFERENCES CITED

Billings, M. P., 1956, Bedrock geology, Pt. 2 of The geology of New Hampshire: 

Concord, New Hampshire State Plan, and Devel. Comm., 203 p.

Cady, W. M., 1967, Geosynclinal setting of the Appalachian Mountains in southeastern Quebec and northwestern New England, in Appalachian tectonics: 

Royal Soc. Canada Spec. Pub. 10, p. 57-67.
QUIMBY AND GREENVALE COVE FORMATIONS IN MAINE LIT

Green, J. C., 1964, Stratigraphy and structure of the Boundary Mountain anticlinorium in the Errol quadrangle, New Hampshire-Maine: Geol. Soc. 

America Spec. Paper 77,78 p.

Harwood, D. S., and Berry, W. B. N., 1967, Fossiliferous lower Paleozoic rocks 

in the Cupsuptic quadrangle, west-central Maine, in Geological Survey research 1967: U.S. Geol. Survey Prof. Paper 575-D, p. D16-D23.

Osberg, P. H., Moench, R. H., and Warner, Jeffrey, 1968, Stratigraphy of the 

Merrimack synclinorium in west-central Maine, in Studies in Appalachian 

Geology Northern and Maritime (Billings Volume): New York, John 

Wiley and Sons, p. 241-254.

Pavlides, Louis, 1966, Meduxnekeag Group and Spragueville Formation of 

Aroostook County, Northeast Maine, in Changes in stratigraphic nomenclature by the U.S. Geological Survey, 1965: U.S. Geol. Survey Bull. 1244-A, 

p. A52-A60.

Pavlides, Louis, and Berry, W. B. N., 1966, Graptolite-bearing Silurian rocks of 

the Houlton-Smyrna Mills area, Aroostook County, Maine, in Geological 

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Pavlides, Louis, Boucot, A. J., and Skidmore, W. B., 1968, Stratigraphic evidence for the Taconic orogeny in the Appalachians, in Studies in Appalachian Geology Northern and Maritime (Billings Volume): New York, John 

Wiley and Sons, p. 61-82.

St. Julien, Pierre, 1965, [Geologic map] Orford-Sherbrooke area, Richmond, 

Sherbrooke, Shefford, Brome, Stanstead, and Compton Counties [Quebec]: 

Quebec Dept. Nat. Resources, Mineral Deposits Services Map 1619.

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Williams, Howel, Turner, F. J., and Gilbert, C. M., 1954, Petrography an introduction to the study of rocks in thin sections: San Francisco, W. H. Freeman and Co., 406 p.

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