Essex County, Massachusetts - Chapter 1: Geography and Geology of Esseix County, 1922

The geology and geography of Essex County is most complicated and difficult. Its rocks are ancient, the roots of old mountains, greatly changed by the heat and pressure accompanying earth movements and the intrusion of molten rock. Its soils have been formed and distributed during successive glacial periods, by the ice, by fresh waters as the ice receded, by sea waves and the winds, as the county was emerging after being covered by the ocean. It is a subject for a scientist. One who would know the detail for his home town may find full treatment in the monograph on the "Physical Geography of Essex County" by John H. Sears, published in 1905 by the Essex Institute.

The geography of the county, however, affects the life of its residents intimately, A farmer must know the origin and nature of its soils, to develop his lands with intelligent wisdom and highest profits. The Chamber of Commerce of a city will plan its development to best advantage when its members know the nature as well as the appearance of their civic environment. The thousands who traverse the highways of the county in automobiles will find keener pleasure at every hill and plain, beside lake or river, if they know something of the origin and significance of these features of our varied scenery. Though details be left to scientists, anyone may know the main truths of our geography, and a simple statement about our lands and waters should be of appealing interest.

Following the Newburyport turnpike up hill and down dale, or any county road, the land seems a confusion of hills, swamps and plains. But view it from a distance - from the railway, or the ocean, toward the hill crests that extend from far west of Saugus eastward to Marblehead, and to Cape Ann. A fairly even, gradually-descending upland line is evident. Nevertheless, even a scientist would have failed to surmise that all the land once rose to this level, and that resistant rock hills are remnants of an ancient upland, were it not that as one travels westward the valleys occupy less and less area, the hilltops broaden and coalesce until they foi-m the Berkshire plateau, trenched by the valley of the Deerfield and overtopped by summits like Monadnock that slow erosion never reduced to the common level.

Mountains are the result of folding or breaking of the earth's crust, uplifting great domes or blocks of land, which are then carved into peaks and slowly worn down by weather, water, and wind. Our Essex rocks are the remnants of tilted strata, and of dikes and masses of other kinds of rock that were forced upward in a molten state into all cracks in the folded and fractured strata, or were crowded between rock layers as great masses, such as the granites in and near Peabody and on Cape Ann. It is estimated that the broad upfold or anticline that extended from Cape Ann far to the southwest, and included at least all the southern half of the county, has lost by erosion a depth of two miles or more of strata.

Only tough roots of the mountains are left, only hill remnants of the plateau. The mountains were slowly eroded during ages when the earth's crust here was fairly stable. At last the rivers swung lazily in broad valleys, little lower than the divides between them, on the gently-rolling lowland they had formed. Then came uplift. The rivers flowed swiftly down the steepening slope and cut valleys in the almost plain, or peneplain, that had become an upland. Far inland on hard rocks these valleys are deep and narrow still. Near the ocean they are of course shallow, and they have broadened and branched until they occupy more space than the hills that reach the old upland level.

Indeed, Nahant lies within a broad lowland - the Boston Basin, that extends from the hills of Lynn and Saugus to the Blue Hills of Milton. Between the Essex county anticline and another south from the Blue Hills is a deep suncline. During long geologic time this was a bay, where sediments accumulated to a great depth, as it slowly folded downward. Earth movements followed, the basin rocks were folded and fractured between the old land masses to north and south. A long line of fracturing fomied along the southern flank of the Essex anticline, a similar fracture line just north of the Blue Hills. Between them the Boston Basin was lowered. When the region was slowly reduced to a peneplain the new rocks north of the line of fracture were worn away. When the peneplain was upraised, the weaker rocks within the basin were more quickly removed, and the resistant rim stands today as the long broken line of rugged hills, on which lie the Middlesex Fells, Lynn Woods and the Salem Pastures.

All this is vital; it determines life. The Boston Basin, into which Essex county extends, contains a fourth the population of all New England. Yet the uplands of its rim are as typically deserted as our remoter uplands. Blueberry pickers on Salem pastures find forgotten roads, old pear trees and wild apples, traces of long-past occupation; but until recently there were only two homes in the three miles between the thick-set houses of Lynn and Salem, only two town ways that cross these wastes of ledges, cedars, and barberry bushes. Lynn Woods and the Fells are mgged and picturesque for parks, but unsuitable for culture, inhospitable for home sites. In fact, the entire upland area of the county north of the Boston Basin and back from the harbors of the coast and the industrial cities of the Merrimac has been a region of decreasing population, of abandoned farms, like all the New England uplands. And the same characteristics that have discouraged agriculture have attracted summer boarders, cottagers, campers - the main industry for much of rural New England. To understand the growth of our factory industries, the decline of agriculture, and the consequent shifting of population in the county, however, other features of our geography must be studied.

The old land of Essex County, with its broad valleys, should have correspondingly mature drainage, with rivers that have worn down to an even slope all waterfalls, and have filled with sediment or drained and worn away every lake. Yet even the Merrimac has rapids at Mitchell's Falls above Haverhill and at Lawrence, and there are falls and natural mill sites on every smaller stream. There are lakes, ponds and swamps in every town of the county and in such numbers that no one has ever counted the multitude of lakelets and pond holes that gather the rain waters every spring. Follow our upland south to counties of Virginia and the CaroJinas, and lakes are lacking, falls are few. For our water powers and beautiful lakes we are indebted to the great glacier that overspread half of North America and moved out over Essex County southeastward to Cape Cod and the islands and shoals beyond, which were formed by the glacial deposits of land waste.

Years ago geologists gave no satisfactory account of our rounded ledges, the great boulders that rest on unlike rock, the plains and hillocks of gravel and sand that floor our valleys, the lakes and waterfalls of our streams. When the same forms were found at the front of Greenland and Alaskan glaciers in process of formation, their origin was clear. Ages ago New England was elevated, Essex County was inland, the rivers wore valleys deep that are now half filled with sands, the shore was far east of Marblehead and Rockport. The climate was colder on the high interior; snow accumulated, glaciers formed, that covered our highest eastern mountains and moved sluggishly southward and outward to the ocean. They scoured away the soil and rotten rock on the surface of hills and valleys, then used the harder fragments held in the glacier, with all the force of the mountain of moving ice above them, to rasp and plane the ledges below. The hills were rounded on their northern shoulders; they broke away on southem slopes, forming cliffs. This is still their usual form, for probably less than 10,000 years have passed since the glacier disappeared. The glacier moved vigorously through north-south valleys, deepening them. Such are the valleys entering the Boston Basin from the north, that from Essex to Manchester, and the one which separates

When the glacier retreated, all the land waste in its dirty ice was dropped in confusion across the county. At times the glacier was moving* forward, yet melting as fast as it advanced. Boulders, sand and clay were dropped together at its stationary front, a frontal moraine. The finer materials were washed away. The boulders remain as the long belts or low ridges of rough ledge fragments that cross Cape Ann over Dogtov/n Commons, and those found extending from east to west in Lynn Woods and through the wild lands of South Peabody. Another boulder moraine extends from Newbury Old Town to Byfield, then south to Long Hill in Georgetown. More frequently the ice was stagnant near the front, but so covered with dirt that it melted very slowly. Streams from the melting ice farther north gushed foi'th at the ice front, full of sands and rock flour. At this time the land had sunk, perhaps under the glacier's weight, so the streams issued into the sea and their waters were checked and dropped their gravels and sands to form deltas in front of the glacier, like those on glacial rivers in Alaska today. The clays were carried forward into sheltered coves of deeper water and deposited there. We know this, because some of the gravels have the rounded pebbles and other characteristics of our present sea beaches, and the clays contain fossils of the same marine shells that are found in waters off Arcti<; shores today. Hence the soils of the valleys and lowlands of the county are largely sands and gravels, with occasional clay beds.

There were several main lines of drainage to the ice front across Essex County, by streams that probably flowed mainly beneath the glacier in ice tunnels they had formed. These tunnels often became choked with small boulders and gravels, so that when the ice melted, they were left as steep ridges that wind about just as the sub-glacial streams wound beneath the glacier. These narrow winding gravel ridges are called eskers. They lead south to gravel and sand plains that formed at the glacier front, and toward clay beds. One line of drainage was through Amesbury, where the esker ridge is seen crossing the highway to Merrimac, a little west of the town. Southward it broadens to form the sand ridge on which Newburyport is built, and is followed by High street nearly to Newbury Old Town. Another esker line passes over Red Oak Hill in Merrimac, then just east of the Whittier homestead in Haverhill, and into Groveland, where it is joined by a tributary line of eskers and sands from West Haverhill. It then passes south through the Boxford plains, past Topsfield and along the east side of Wenham Swamp and Wenham Lake, thence across Beverly to the harbor and the sea. A third train of sands enters from New Hampshire, crosses Methuen, Lawrence and Andover, and includes the well-known Indian Ridge there, then passes into Middlesex County. There are other shorter series of eskers and sands, for example, that along South Salem froa'n the Normal School on to the sand plains that reach from south of Forest river to the ocean front at Beach Bluff.

The northern border of this plain is typically steep and irregular, with many gravel hillocks and short ridges, called kames, and many little enclosed valleys among them, that are called dungeons in Marblehead. The stagnant edge of the glacial ice had many crevasses and detached ice blocks. Outflowing streams filled in gravels between and upon the ice masses. After the main glacier had disappeared, these covered and protected ice blocks also melted. The gravels and sands slumped down, with slopes steep and confused in proportion to the depth and complexity of the fonner ice margin.

Forest river flows eastward along the line of the vanished glacier front. If Salem Harbor had not been occupied by ice, but had been filled high with sands. Forest river valley would have been a lake. In just this way Wenham Lake and Wenham Swamp occupy the lowlands, filled by great ice blocks when the sand plains of Beverly were built in front of them. . Much of the southern and eastern shores rise steeply to the plain level, marking the ice contact line when the sands were deposited. While a few of the Essex County lakes occupy rock basins that were not filled with glacial deposits, like Forest Pond, Middleton, nearly all our lakes and ponds and many swamps lie within or beside sandy plains and slopes and occupy the holes left by the melting of ice blocks. Many have steep shoi'es rising to sand plains, usually on the southern sides, to mark the old ice contacts. There were many smaller ice blocks buried in the sand, whose site is marked by shallow depressions in the plains, called kettle holes. They are usually dry, as the pondlets of spring time soon drain away.

These plains are usually too gravelly and sandy to be fertile. They make better roadways and building sites than rough hill slopes, but they are less favored for farms and pastures than the gentle slopes of glacial till, where the soil contains much clay and retains moisture. The early settlers often placed their town centers and buildings upon these plains ; they are well adapted for use for fair grounds, race tracks, training fields for the militia, aviation fields, baseball fields. In some places, as at Danvers, South Peabody, Marblehead, the soils of the plain are finer, and being free from boulders are well adapted for use by market gardeners, who can afford to provide fertilizers as may be needed. The well-known milk farms of the Hood Milk Company in Beverly and Topsfield are not on the sand plains, however, but on Cherry Hill and one of the broad, smooth hills crossed by the Newburyport Turnpike ; for the soil of many hills and slopes was formed beneath and within the glacier, where rock fragments and rock flour are intermingled. They are therefore moister and more fertile than the gravel and sand plains from which clays were swept by the glacial streams.

The scores of gently-curving, lens-shaped hills of glacial till, called drumlins, that are found from West Peabody to Ipswich and northward into New Hampshire are as marked a feature of Essex geography as our lakes. They are most abundant along the Merrimac, where Whittier sings, "The hills roll wavelike inland." They occur in groups and pairs, or singly, like Pigeooi Hill in Rockport. There are many in the Boston Basin, but none on the rough highlands back of its rim, and none on Cape Ann except Pigeon Hill. They are composed of till, clay which includes stones and boulders, just as dropped and overridden by the ice, compressing and shaping them. We know how sand plains and their depressions were formed; geologists do not know just how drumlins formed. Perhaps they gathered beneath the glacier as sand bars form in rivers. They are smooth, fertile, beautiful features of our landscape, rising to summits higher than the low monadnocks of the uplands near the Boston Basin. The rock hills of Lynn Woods and Saugus are less than 300 feet above tides, the drumlins of North Andover rise to nearly 400 feet above sea level. They afford fine outlooks; the Danvers Asylum has a commanding position upon a drumlin. But any one of them might well have been called Bare Hill, like that east of North Andover center, for their steep side slopes turn the country roads away. There are nearly 200 drumlins in the county, most of them so conspicuous as to be well-known by local names. They are represented in every town and city except Gloucester and Manchester on Cape Ann, Salem and the five communities on the rough southern border of the county.

Our most recent geographical features, still in process of marked change from year to year, are along the coast, where waves, tides and currents are at work. There were doubtless drumlins and gravel deposits east of our present shores. The outer drumlin islands of Boston harbor show clay seacliffs and different stages of destruction, while reefs of boulders off Hull and Nantasket mark the site of drumlins that have been entirely washed away. The undertow has carried finer wastes into deep water offshore or to the quiet waters of bays. Storm waves breaking far out in shallow water built bars of sand ; alongshore currents brought land waste to them, swept from the cliffs of bolder coasts nearby. Master storms raised the bars above low tide level, the wind heaped the finer sands into hillocks, the bar broadened and sand dunes rose well above the highest tides.

Some of these bars curve gently from the shore to an island, and are called tombolos. In this wise the three islands of Nahant, Bass Point and Little Nahant were tied together and to the mainland as a peninsula. Similarly, Marblehead Neck is tied to the shore at its southem end, and the island of Gloucester is reached by a highway from Cape Ann mainland along a barrier beach, although the old seaway to Squam river has been re-opened as a canal. Other wave-built bars separate a marsh from the ocean, as at Phillips Beach, Swampscott, where the fresh waters seep through the beach in springs at low tide. Our greatest barrier beach is Plum Island. At its southern end, off the Ipswich shore, it starts from the remnants of drumlins; its dunes, outer beach and inner marshes extend thence northward to where the outflow of the Merrimac prevents waves and currents from making the bar continuous with Salisbury Beach.

Behind every bar is a lagoon. The smaller enclosures are shut from the ocean, as at Swampscott beaches. Larger ones are swept by the tides. The eel grass in the deeper waters of a lagoon catches the waste that sinks into the grasp of its tangle of blades at every turn of the tides, and the lagoon becomes shallower. The mudflats, bare of grasses, exposed twice daily, are upraised very slowly. Marsh grasses build outwards from the shore at high tide level, catching waste floated by streams from the land and by currents irom along shore. Thus the lagoons are now occupied by broad marshes, intersected by winding tidal creeks, whose currents undercut and wear back the outgrowing marsh sod, maintaining one of the interesting balances between opposing natural forces. Broad marshes boi'der Squam river in Gloucester and lie behind the bars of Coffin's Beach, Castle Neck in Ipswich, Plum Island and Salisbury beaches to the north. Creeks and canals give a waterway behind the bars. Years ago the marsh hay was highly valued, and farmers from miles inland went "mashin" every August at the right run of tides. Years hence the tides may be shut out by dikes, as is true of the polders of Holland, and these marsh soils may become very valuable farm lands. Meanwhile, their mudflats give us a harvest of clams yearly. The Saugus marshes are more likely to be filled in and used as factory sites; for they are underlaid by firm clays well able to support factory buildings, and are convenient for rail and ocean transportation of supplies and products.

A sand bar coast repels life, for it offers scant refuge from storms for either merchant vessels or pleasure yachts. Hence Plum Island was long almost a desert, save for its lighthouse, life-saving station, and one farm on the drumlin soils off Ipswich. Because sea front lands are all pre-empted along our rock shores, there are many summer cottages today at the northern end of Plum Island, easily reached by automobile over the causevv^ay from Newburyport. But there are no large and gi'owing cities between Portland and Gloucester, although there are many summer colonies dotted along the sand bar beaches from Essex County northward. From Cape Ann to Lynn, however, the North Shore of Massachusetts Bay is bold, rocky, irregular, with good harbors. A group of cities is growing about Salem harbor, once a leading port for commerce with far-eastern lands, now a center for the busy industries of Salem, Peabody, Beverly and Danvers. The harbor of Gloucester, set far out toward the fishing grounds, remains the leading port for trawlers and for salt and smoked fish. All the adjacent bold shore lands and the hills inland are occupied by costly summer cottages that are often mansions. Nahant was famous generations ago. Lynn shore drive, leading to the great hotel at Swampscott, is famous fai* beauty today. Marblehead Neck and harbor are renowTied as a yachting center. Society extends its sway back from the estates of millionaires at Beverly and Manchester-by-the-Sea to the golf and polo fields of Hamilton. The life of this bold North Shore, v/ith its rocky islets, frequent fine harbors, its alternating cliffs and pocket beaches, is vastly unlike the deserted dunes and long straight beach of Plum Island.

The rocks of the picturesque coast are so resistant that storms have made small progress in cutting the ledges back. Where the dikes that cross the ledges and cliffs are relatively weaker, they have been cut out by the waves, forming chasms, purgatories, spouting horns, v/here the water dashes in and is throv/n up with great force at the narrowing and abrupt inner end. There is endless variety in shore forms both in details and in combination of harbors and patches of marsh, outlying reefs and islands, sloping ledges and shai-p cliffs, pocket beaches of cobbles, pebbles, or singing sands, whose minute crystals give a musical sound beneath passing footsteps. No wonder Whittier or Longfellow loved these home shores, praised their beauties and retold their legends in verse.

Essex County is lower than when its valleys were formed, hence their outlets seaward are now filled by salt waters as safe harbors - drowned valleys. The sand plains are higher than when many of them were formed; the plain on which the center of Lynn is built is continuous with the harbor mudflats; it is an upraised sea bottom, a coastal plain. Nevertheless, the coast has in recent centuries slov/ly sunk again. There are trunks and stumps of pines, oaks and other large trees to be seen at very low tides on several beaches and marshes along our shore, and it is clear that they once grew where they are still rooted, proving that the soil was formerly above high tide level. The depth of ledges below low tide level as recorded a century ago was two feet less than their present depth. But the change takes place so slowly that it has only partially offset the shoaling of harbors.

During the centuries since glacial time, and the periods between successive continental glaciers, there have been more marked invasions of the land by the sea. Remnants of old bars, with their dunes, now grass grown, and clay beds in the former lagoons, are found at the eastem angle of Georgetown, and in Topsfield along the road east of Fish Brook. Seaworn cobbles are found beneath later glacial deposits. Sea sands laid in horizontal beds, without the cross bedding characteristic of the frontal deposits on glacial deltas, cover extensive areas in Andover and southward into Middlesex County, also in Georgetown. While the glacial ice actively rasped away solid rock on exposed ledges and through valleys where the ice flow was concentrated, at other places it overrode loose deposits of previous glacial invasions. All these intermingled forms of earlier and later deposits make details of our geography as uncertain as they are interesting. The main facts, however, are simple and clear.

The geographic resources of the county are not remarkably rich. As in most lands of folded rock strata, percolating heated waters have dissolved scattered minerals and deposited them in veins and lodes. Lead, copper, silver ores are found in the county, even gold. They have been mined. But the deposits are neither rich nor extensive. More silver has been sunk in the mine at Newburyport than has been taken from it. There are deposits of bog iron ore in our lakes, streams and swamps, from water leaching through glacial sands, which were a source of supply for the colonists at the early Saugus iron works, although no longer used. There is more profit now in spring waters of the county, some pure, some desirably impregnated with minerals, when bottled and sold for table use, than in mineral deposits from the underground waters of past ages.

But the county has some valuable earth resources. There are many quarries, active or abandoned, in the granite districts north of Lynn, while those of Gloucester and Rockport, next the shore, and able to ship building stone and paving blocks cheaply to coast cities and to sell their waste as a by-product for building breakwaters, are of large commercial importance. The tough rhyolite rock that borders the Boston Basin, as at Lynn, does not break along joint planes into rectangular blocks like granite, yet it has been used for buildings and is now actively quarried at several hills and cliflfs for road material. And the brick clays of Lynn, Peabody, Danvers and other towns have been valuable for local supplies and should continue in use, even though better clays for pottery are found west of New England, and despite the use of cement and re-enforced concrete, where brick or granite were employed aforetime.

There are a thousand details of fascinating local geography worth setting forth: account of great glacial erratics, like Agassiz Rock in South Essex ; of glacial markings on smoothed ledges, notably the deep rock groove in the park at Salem; mention of details of river action, like^the abandoned channel of the Merrimac in West Newbury that undercut the clays of Long Hill drumlin; description of mill sites and water supply sources - but these best remain for studies of local geography. Viewing our geography in the large, its trends are those of the early rock folds, from southwest to northeast. The main rivers still follow the line of the strike of the rocks, and the Merrimac river and the North Shore are fairly parallel, with the Ipswich river winding between. Likewise, there is a line of busy industrial communities at the north from the waterpower sites of Lowell and Lawrence to the waterway from Haverhill to Newburyport; and a parallel line of harbors and factory chimneys at the south from west of Lynn past Salem to Gloucester. Between are the scattered farms and villages, summer settlements and estates of the mid-county, less populous than years ago. Viewing details, they are mainly governed by glacial deposits, for sandplains and drumlins determine the windings of the rivers, the location of lakes and swamps, of roads and hamlets, homesteads and fields. This returns us to the truth maintained at the outset, that our geology and geography repay study, since they constitute our environment and vitally affect our life. This chapter merely introduces the subject, even as it does this county history.