when studied with the microscope.
Enstatite. In micro-crystals in the olivin gabbro of Salem Neck.
Bronzite. Pound with the enstatite on Salem Neck, and also in a
coarse pegmatitic mass on Misery island, Salem Harbor.
Hornblende. Irregular crystals are abundant in the hornblende
granite of Peabody and, microscopically, it is common in the diorite,
syenites, and the dike rocks.
Tremolite. At the Devil's basin, Newbury.
AcTiNOLiTE. Long crystals are found at Bass Point, Nahant, and
it is also found in a large pegmatite boss in the quarry of the Rockport
Granite Co., Rockport.
AsBESTUS, pseudomorph of Actinolite. A vein six inches wide, in
the diabasic norite, occurs at Bass Point, Nahant.
Arfvedsonite : Alkali Hornblende. Irregular crystals are found at
Salem Neck, and larger masses in the elasolite zircon syenite on Coney
island, Salem harbor.
AiNiGMATiTE. Rare, but found in microscopic masses in the elaeo-
lite zircon syenite. Great Haste ledge, Salem harbor.
Cossyrite. In microscopic crystals in the augite syenite at Magnolia.
Glaucophane. a deep blue hornblende. In massive forms in the
augite hornblende granite at Pickering's point, Salem, and in the granite
porphyrite at Marblehead Neck, etc.
Chrysolite: Olivin. Found in porphyritic crystals in olivin basalt
dike rocks, Salem Neck, etc.
Fayalite. a large mass, at a depth of sixty feet, occurs in the quarry
of the Rockport Granite Co., Rockport.
Danalite. In irregular masses and microscopic blebs scattered
through the hornblende biotite granite at the quarry of the Rockport
Granite Co., Rockport, and also at the Pomeroy quarry, Gloucester.
Garnet. Garnet occurs plentifully in a garnet schist outcrop between
Powder House hill and White's hill in Essex, and elsewhere in the County.
Fig. I 19.— APORHYOLITE, SHOWING WEATHERED SURFACE.
High Rocl<, Marblehead Necl<.
Fig. I 2 0. -BANDED APORHYOLITE, SHOWING THE FLOW OF THE MAGMA PREVIOUS TO ITS
CONSOLIDATION. SIZE OF SPECIMEN, 14 x 20 INCHES.
Bowden's Point, Marblehead Neck.
THE MINERALS OF ESSEX COUNTY 241
Almandite Garnet. Abundant in the biotite muscovite granite at
Grossularite Garnet: Cinnamon Stone. In a drift boulder at
Zircon. Crystals with double terminations are abundant in the
elasolite zircon syenite at Salem Neck, Beverly, etc.
Vesuvianite. Specimens from a vein in the serpentine at the Devil's
basin, Newbury, were analyzed by Prof. W. O. Crosby, and determined
Epidote. Veins with fine drusy crystals are found at Egg rock, near
Nahant; in the diabase at East point, Nahant; and also in the rhyolites
at Marblehead, Clifton, etc.
Allanite. Radiated crystals are foimd in the diorite at Beverly,
and long slender crystals are found in the augite syenite at Beverly and
West Gloucester and in the granite at Swampscott. The specimen deter-
mined as orthite and described in the "American Journal of Science
and Arts," Vol. XXXIII, page 198, should undoubtedly be referred to
Orthite. Found in radiated crystals in the hornblende biotite grani-
tite at the quarry of the Rockport Granite Co., Rockport.
ZoisiTE. This occurs in fine blue crystalline masses in the zoisite
gneiss and the hornblende epidote gneiss at Andover, Georgetown, and
loLiTE. Found in corderite gneiss at Marble Ridge, North Andover.
Phlogopite Mica. In granitite at Rockport.
BioTiTE Mica. In augite syenite at Salem Neck and Beverly, and
also in granitite at Rockport.
Lepedomelane. Found in hexagonal plates of a bronze color in the
Pomeroy quarry, Gloucester.
AsTROPHYLLiTE. In the quarry of the Rockport Granite Co., Rock-
Muscovite Mica. Common in the biotite muscovite granite at
Andover, Methuen, and Rowley.
Lepidolite: Lithia Mica. In mica-schist at Ballardvale, Andover,
Ward's Hill, Bradford, and Methuen.
Sericite. This occurs in irregularly banded plates in the jaspelite
at Saugus Centre, etc.
Scapolite: Wemerite. In 1890, microscopic grains of scapolite were
discovered in thin sections of the hornblende granite collected at a quarry
THE MINERALS OF ESSEX COUNTY
on Humphrey street, Swampscott, which is beheved to be the only record
of this mineral having been found in granite.
Cryophyllite. In the hornblende biotite granitite at Rockport/
Annite. FotHid in the hornblende granite at Rockport.^
^ Chemical analyses of three sections of cryophyllite from Rockport, made by R. B.
Riggs, of the United States Geological Survey, gave the following results.
A. Brilliant, broadly foliated, blackish-green variety.
B. Paler, dull green, less Ittstrous, probably somewhat altered.
C. Granular, resembling chlorite, minute six-sided prisms, color dark green.
Less oxygen — O equivalent to F 2.86
4. 1 1
^ A chemical analysis of the annite from Rockport, made by R. B. Riggs of the United
States Geological Survey, gave the following result:
HjO at 105° 1
H^O above 105° J '^•'^
Fig. 121. — APORHYOLITE CONCRETION, 9 INCHES IN DIAMETER.
Fig. 122.— APORHYOLITE CONGLOMERATE, 12x14 INCHES IN SIZE.
South Gooseberry Island, Salem Harbor.
THE MINERALS OP ESSEX COUNTY 245
El^olite. This occurs in large irregular crystalline masses in the
elseolite zircon syenite at Beverly, Salem Neck, etc.
Nephelite: Nepheline. Found in small micro-crystals in the augite
nepheline syenite at Salem Neck, Beverly, and Gloucester.
Cancrinite. This occurs in minute irregular masses in the elseolite
zircon syenite at Salem Neck where it is lemon yellow in color. It is more
abundant at Great Haste ledge and the Ram islands, Salem harbor, where
the color is grayish to brown.
SoDALiTE. In coarse pegmatitic masses in the elaeolite zircon syenite
at Salem Neck, Great Haste ledge, and Beverly shore.
Hydronephelite. In radiated crystals in the elseolite zircon syenite
at Salem Neck.
Anorthite. a large mass of this feldspar occurs at East point,
Nahant, near the residence of Hon. H. C. Lodge.
Labradorite. This occurs in large crystals, some of which are three
inches long by one and one half inches wide, in the gabbro at Bay View,
Davis Neck, and Lanesville in Gloucester; also in porphyritic dike rocks
in various localities.
Albite. Fine glassy, multiple-twinned crystals are found at the
Pomeroy quarry, Gloucester.
Orthoclase. Simple and twinned crystals are found in pegmatitic
masses in the granite at Rockport. Common in the granite.
Microcline: Amazon Stone. Specimens of a bright verdigris-green
color are found at Briscoe hill, Beverly, and at Gloucester, and Rockport.
Microcline microperthite : Soda Microcline of Brogger. Found in
coarse crystalline masses in the eteolite zircon syenite at Salem Neck.
Orthoclase microperthite : Albite and Orthoclase intergrowths. In
the elffiolite zircon syenite at Coney island, Salem harbor.
Sanadin. In crystals from the Bostonite porphyry (Rosenbusch) , a
dike rock on Coney island, Salem harbor.
Anorthoclase. In crystals in the keratophyre at Marblehead har-
Prehnite. Rare; in reniform or globular masses in the hornblende
gabbro at Nahant.
Natrolite. This occurs as a secondary pseudomorph of elaeolite on
Salem Neck and in amygdules in the amygdaloidal melaphyre at Rowley.
Steatite: Soapstone. In a massive bed associated with the serpen-
tine at Newburyport.
» See Bull. M. C. Z., Geol. Sur., Vol. II, No. 9, p. 167.
246 THE MINERALS OF ESSEX COUNTY
Talc. The fine granular variety known as French chalk is found at
Newburyport near the silver mines.
Serpentine : Noble Serpentine. Of a rich oil-green color at Devil's
Serpentine : Common Massive Serpentine. At Devil's den, Newbury.
Serpentine : Foliated Serpentine : Marmolite. At Devil's den, New-
Serpentine : Picrolite. At Devil's basin, Newbury.
Serpentine : Picrosmine. At Devil's basin, Newbury.
Serpentine: Baltimorite. At Devil's basin, Newbury.
Serpentine : Chrysotile : silky fibrous. At Devil's basin, Newbury.
Serpentine: Massive Serpentine, dark colored variety. At Lynn-
Kaolinite. At Kent's island, Newbury, and at Little Niagara river,
Tourmaline. Long acicular crystals, some of which in finely radiated
groups and black in color, are found at South Groveland.
Andalusite. In veins of andalusite slate at Nahant, and near Flax
Andalusite: Chiastolite. Crystals are found in glacial drift at the
Castle, Castle river, Ipswich.
Fibrolite. In the corderite gneiss at Marble Ridge, North Andover.
Titanite: Sphene. Micro-crystals are found in augite syenite at
Salem Neck, Beverly, Magnolia, etc.
Bastite; Schiller Spar. Resulting from the alteration of pyroxine
diallage in the diabasic norite, Nahant.
Finite. Pseudomorph of orthoclase; at Eagle island, Little river,
and Kent's island, in Newbury, etc.
Jeffersite. In broad crystalline plates resembling biotite mica ;
northwest side of Powder House hill, Beverly, and in the old lime-pits
near Stevens' pond, Boxford.
Pennenite. In the Pomeroy quarry, Gloucester.
Delessite. This occurs as thin folia in seams of diorite at Salem,
and in diabase dike rock at Bradford, etc.
Uralite. a paramorph of hornblende after pyroxene. This min-
eral is abundant, microscopically, in the quartz augite diorite of New-
buryport, Carr's island, etc.
Fergusonite. Found in the granite at the quarry of the Rockport
Granite Co., Rockport.
THE MINERALS OF ESSEX COUNTY 249
Ruby Spinel. Rose colored specimens in massive form were fotmd in
the limestone at East point, Nahant, in 1905.
Apatite: Phosphate of Lime. Microscopic crystals occur abundantly
in diorite augite syenite, and many dike rocks.
Apatite: var. Guano. Found incrusting the rocks at Great Haste
ledge and Halfway rock, Salem harbor.
Calcite: Calc Spar. Often found in good rhombic crystals in the
amphibolite gneiss at Putnamville.
Calcite: Dogtooth Spar. Near the Tri-Mountain House, Bass Point
Calcite : Massive Granular Limestone. Found in large masses at the
Devil's den and Devil's basin, Newbury, and at the old lime-pits in Box-
Calcite : Massive Blue Limestone. Interstratified with quartzite sand-
stone and slate in the carboniferous rocks at Topsfield.
Calcite: Statuary Marble. Specimens, pure white and fine grained,
occur at the Devil's den, Newbury.
Calcite: Silicious Limestone. This belongs to the Olenellus Lower
Cambrian period and occurs at Archelaus hill, West Newbury, at Rowley,
Dolomite: Magnesian Limestone. Found in veins in the serpentine
at the Devil's den, Newbury.
Ankerite. Good rhombohedral crystals are fotmd in the granite at
the Pomeroy quarry, Gloucester.
Magnesite : Brown Spar. Found in the old serpentine ledge at Lynn-
field Centre, and at Boxford and Newbury.
Siderite: Spathic Iron. Massive crystalline forms are found asso-
ciated with the iron pyrites and galena at the Chipman mine, 'Newbury,
and (rare) in small compound scalenohedrons and rhombic crystals in-
crusting the albite feldspars at the Pomeroy quarry, Gloucester.
Siderite, bronze var. In the Newbury mining region. The usual
form is granular in structure.
Malachite: Green Carbonate of Copper. Found associated with
gray copper at the Osgood mine, South Georgetown.
Azurite: Blue Carbonate of Copper. At the Osgood mine, South
Quartz. A quartz crystal, an inch broad, a pseudomorph of fluorite,
deep scarlet in color, was found in the granite at the quarry of the Rock-
port Granite Co., Rockport.
250 THE MINERALS OF ESSEX COUNTY
Coal: Earthy Brown Coal. At the east side of Nahant, near the
old iron mine.
Bog-butter: Oxygenated Hydrocarbon. Three feet oelow the sur-
face, at Clifton, Marblehead.
Yttrocerite. On massive smoky quartz in the Rockport Granite
Company's quarry, Rockport.
THE QUATENARY PLEISTOCENE PERIOD : GLACIAL ICE EPOCH
The landscape of Essex County, and in fact of all New England, owes
its generally rounded outline and level sky-line to the effect of an ice-
sheet, or continental glacier, which covered this region in the ice epoch.
(See Fig. 124.) The thickness of this ice-sheet is computed to have been
at least 2,290 feet. The summit of Mount Desert island, on the coast of
Maine, is glaciated with fine strise, or scratches, at an elevation of 1,527
feet above mean sea-level. Prof. Louis Agassiz is quoted as saying,
that no glacier could cross a ridge unless its thickness was at least one
half of the height above the ridge, and by this rule it may be judged that
the ice-sheet on the coast of Maine was 763 feet in thickness over the
summit of Mount Desert. To this should be added the height of Mount
Desert — 1,527 feet, giving a total thickness of the ice-sheet above mean
low water on the coast of Maine of at least 2,290 feet. As there is no ma-
terial difference between mean low water at Mount Desert, and at Essex
County, it is fair to presume that the ice-sheet over the latter region was
also at least 2,290 feet in thickness. Inland from the coast one hundred
and twenty-five miles is Mount Greylock, the highest elevation in the state
and 3,555 feet above mean low water (Appalachian Club). By follow-
ing the rule laid down by Professor Agassiz, the thickness of the ice-sheet
in the Mount Greylock region must have been 5,301 feet, indicating a
gradual slope of sixteen feet to the mile from Mount Greylock to the coast
of Essex County.
At the close of the Tertiary period and during the ushering in of the
Quaternary or Pleistocene period, occurred the great uplift or elevation
of the land surface amounting to several thousand feet in North America.
Probably this uplift was from one hundred and eighty to two hundred
feet in Essex County. It raised the bed of the sea to high land from one
to two hundred miles out from our present coast for the distance reaching
from Jeffery's shoal to beyond Cape Sable. This uplift caused the rivers
and streams to cut down their valley beds, thus forming the deep fiord-
like channels and hollows which now reach out into the sea. Another
254 THE QUATENARY PLEISTOCENE PERIOD
result of this uplift of the land surface was to change the climate from
temperate to boreal. This arctic climate caused a glacial ice-cap to form
over the uplifted land surface. It expanded from a center of accumula-
tion in the Canadian highlands, and moved towards the southeast from
the northwest, which is the direction in which it is known to have passed
over Essex County as recorded by direction of the grooved, scratched,
and striated surfaces of the ledges over which it passed. In many
places it planed down the surfaces and rounded the outlines of hills and
ledges, nearly always leaving fine scratches and striae on their surfaces, a
lasting record of glacial action. Some times even the tools — the rocks
with which these scratches and grooves were made — are found in the
boulder-till. (See Fig. 126.)
Glacial erosion is shown on the surface of bed-rock by grooves and
scratches, or striated lines, and also by prominences of bed-rock which
have been rounded. (See Figs. 70, 127, 128.) On looking northward
from the top of Red Shank hill, at South Georgetown, the land surface
appears like a billowy sea. (See Fig. 129.) This area is covered by a
thin coating of drift-sand and gravel, and the true nature of these
mounds is not apparent until the sand and gravel covering is removed,
when the rounded surfaces of the bed-rock appear. The name Roches
Moutonnees or "sheep backs" has been applied to this formation. A
series of these "sheep backs," covered with drift and growths of forest
trees, occur near the village of Topsfield, and have received the local name
of "sugar-loaf" hills. The bed-rock forming these elevations in Tops-
field is arkose, a conglomerate granite. (See Fig. 130.)
In nearly all parts of the County, the surface of the diorite bed-rock,
wherever it is exposed, is distinctly glaciated. A fine example of a glacial
groove in a hornblende diorite ledge may be seen beside the carriage road
in Ledge Hill park, Salem. (See Fig. 128.) In the bottom of the groove
are long, deep scratches and fine striae, and beside the groove and on its
western side, the whole surface of the ledge is glaciated with short and
long grooves, deep scratches, striae, and chatter-marks.
Similar glaciated surfaces of bed-rock may be seen in North Salem.
In Danvers, nearly all of the diorite bed-rock shows glacial scratches. The
direction of glacial ice-movement across this region is thereby recorded
as having been from the northwest to the southeast. The granite and
syenite bed-rocks also show glaciation, but the scratches and striae have
usually been removed by disintegration, leaving only the rounded sur-
faces to record the work of the glacial ice.
Fig. 125. — QUARRY OF THE ROCKPORT GRANITE COMPAhJY AT ROCKPORT.
Showing the general structure of the hornblende granite rock.
^^^K?/ ' '^ aH ^
Fig. 126.— GLACIATED- STONES FOUND IN BOULDER-TILL AT NORTH ANDOVER.
J stones probably were some of the tools which cut the glacial grooves, striae, scratches, and chattermarks found c
the surface of outcropping ledges.
Fig. 127. — GLACIATED DIABASE DIKE ROCK NEAR FLYING POINT, MARBLEHEAD NECK.
Fig. 12 8. — REMARKABLE GLACIAL GROOVE, 30 FEET LONG, 3 FEET WIDE, AND 5 1-2 INCHES DEEP, ON
THE SURFACE OF A HORNBLENDE DIORITE LEDGE IN LEDGE HILL PARK, SALEM.
The topography of Essex County therefore owes its characteristic fea-
tures to the work of the continental glacier. This glacial drift assumes
within comparatively limited areas, forms so numerous and so varied as to
render the region an exceptional one for study. The bare, rounded surfaces
of the granite and other outcropping bed-rocks tell the story of a grinding
force. The long sloping hills, the drumlins of boulder-till, the "kettle-
holes" or sites where icebergs in front of a retreating ice-sheet had been
buried in over-wash sands and gravels, are all to be seen in various parts
of the County. Ridges, terraces, and cone-like masses of sand and gravel
rising from a gently sloping incline of sand and clay, and leading to a
pond or filled pond, now a peat swamp, alike mark the contact of an ice-
block that was stranded at the present location of the pond or swamp.
Moraines or circular ridges of gravel, and boulder trains or lateral mo-
raines sometimes occupying drainage creases in front of the retreating ice-
sheet, are among the forms assumed by the glacial drift. Another form
is the long serpentine ridge or esker which records the presence of a drain-
age stream flowing under the ice-cap and grading its channel with sand
and coarse gravel. Upon emerging from under the ice these streams
deposited their loads of sand, gravel, and clay in the order of their coarse-
ness, now to be seen in the form of bouldery gravel-banks, sand-plains,
The ideal section of an ice-contact, with alluvium falling against the
front of the ice edge of a glacier, will very well represent the forma-
tion of the kame topography on the south side of Forest river, west from
the electric car sheds, in Marblehead. (See Figs, 131, 132.) These ice-
berg holes are locally known as "the dungeons." They were formed by
detached bergs of ice which became buried in the outwash gravel. When
the ice melted, the covering of gravel fell in, leaving the place which had
been occupied by the ice-block in the form of a steep-sided hole. The
ideal section demonstrates that an alluvial plain, which is built up in front
of a glacier, will overtop the ice and include not only morainic debris but
also blocks of the ice, and when the glacier melts, the overlapping deposit
cannot assume the simple earth slope of the angle of repose, but receives
a hummocky morainic appearance as illustrated in the surface from the
dotted line at E in Fig. 132. This is also to be noted in Fig. 131.
Eskers. — The term esker is here employed to denote distinct ridges
composed chiefly of coarse gravel, angular, subangular, and rounded
boulders, and sand, believed to have been deposited in the beds of sub-
glacial streams, being phenomena of the radial drainage of the conti-
nental ice-sheet. (See Figs. 133, 134.) Continuous ridges of gravel, de-
noting subglacial stream channels, are of rare occurrence in eastern Mas-
sachusetts. There are numerous curved ridges and terraces of some extent
that, without doubt, were formed by gravels deposited from the sur-
face of a waning ice-sheet. The glacial gravels from Bishop's swamp,
an ice-block hole at Danvers, supply an example on a small scale. (See
Fig. 136.) Many similar examples both large and small, may be found
in all parts of Essex County. Typical eskers, continuous for a mile or
more, as previously stated, are of rare occurrence.
A nearly continuous esker, broken by post-glacial erosion and stream-
cutting, may be traced from Groveland, across South Groveland to the
Parker river in Georgetown, and then across Parker river to Four Mile
pond, in Boxford. At the northern end of Four Mile pond this esker
expands into a rolling sand-plain. On the western side of the pond it
again forms into a steep-sided ridge which extends over one mile to the
southeast, where it is obliterated by the Pye brook sand-plain in Box-
ford. This esker is next seen as a continuous ridge at a point about two
miles distant and north of Hood's pond in Topsfield. It may be easily
followed in the valley occupied by the road-bed of the Boston and Maine
railroad to a point near Bare hill in Topsfield, where Mile brook and a
series of meadows have cut through and destroyed the formation. This
esker is next seen in a hilly pasture on the land of John Perkins, south
of Mile brook. Here it becomes very distinct and forms two parallel
ridges. It then crosses the Ipswich road and disappears at the bank of
the Ipswich river. On the other side of the river this ridge may be traced
around the northerly side of Willowdale hill to a point southerly from
the site of the Willowdale mill, where it is flanked on the east by a remark-
able series of reticulated kames exhibiting both knob and basin topog-
raphy, many of the iceberg holes now being occupied by small ponds.
(See Figs. 135, 138). At the Gwinn farm in Hamilton this esker again
appears in a pasture, where the top of the ridge might be observed for a
■distance of over a mile if it were not for the growth of small trees and
bushes which cover it. South of the Gwinn farm (see Fig. 137) it crosses
the road and is then overgrown with hardwood trees for a distance of
nearly five htindred yards to a narrow swamp. Beyond this swamp the
ridge again appears distinctly with very steep sides. At one point it is
■eighty feet from the top of the ridge to the level of the low land in the
swamp from which the esker rises. This section is continuous for over
lialf a mile to the tracks of the Boston and Maine railroad, where recent
Fig. 129. — " SHEEP backs;
OR ROCHES MOUTONNEES, AT SOUTH GEORGETOWN,
ons of bedrock covered by drift gravels.
■ •a'< ,^ ..
•<<- -'."'■ ■■■■ '■■' ■".
-■. '>-■ • 'f. - ■
*^.'. ."•"^' - ■,
♦" «'', ■ i
Fig. 130. — " SUGAR-LOAF" HILL OR ROCHE MOUTONNEE AT TOPSFIELD.
Arkose granite conglomerate covered by a thin coating of glacial drift.