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State of Connecticut
State Geological and Natural History Survey
Bulletin No. 30

 

Drainage Modifications and Glaciation
in the Danbury Region
Connecticut

By

RUTH SAWYER HARVEY, Ph. D.

HARTFORD

Published by the State

1920

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BULLETINS

OF THE

State Geological and Natural History Survey
of Connecticut.

1. First Biennial Report of the Commissioners of the State Geological and Natural History Survey, 1903-1904.
2. A Preliminary Report on the Protozoa of the Fresh Waters of Connecticut: by Herbert William Conn. (Out of print. To be obtained only in Vol. I, containing Bulletins 1-5. Price $1.50, postpaid.)
3. A Preliminary Report on the Hymeniales of Connecticut: by Edward Albert White.
4. The Clays and Clay Industries of Connecticut: by Gerald Francis Loughlin.
5. The Ustilagine? or Smuts, of Connecticut: by George Perkins Clinton.
6. Manual of the Geology of Connecticut: by William North Rice and Herbert Ernest Gregory. (Out of print. To be obtained only in Vol. II, containing Bulletins 6-12. Price $2.45, postpaid.)
7. Preliminary Geological Map of Connecticut: by Herbert Ernest Gregory and Henry Hollister Robinson.
8. Bibliography of Connecticut Geology: by Herbert Ernest Gregory.
9. Second Biennial Report of the Commissioners of the State Geological and Natural History Survey, 1905-1906.
10. A Preliminary Report on the Alg?of the Fresh Waters of Connecticut: by Herbert William Conn and Lucia Washburn (Hazen) Webster.
11. The Bryophytes of Connecticut: by Alexander William Evans and George Elwood Nichols.
12. Third Biennial Report of the Commissioners of the State Geological and Natural History Survey, 1907-1908.
13. The Lithology of Connecticut: by Joseph Barrell and Gerald Francis Loughlin.
14. Catalogue of the Flowering Plants and Ferns of Connecticut growing without cultivation: by a Committee of the Connecticut Botanical Society.
15. Second Report on the Hymeniales of Connecticut: by Edward Albert White.
16. Guide to the Insects of Connecticut: prepared under the direction of Wilton Everett Britton. Part I. General Introduction: by Wilton Everett Britton. Part II. The Euplexoptera and Orthoptera of Connecticut: by Benjamin Hovey Walden.
17. Fourth Biennial Report of the Commissioners of the State Geological and Natural History Survey, 1909-1910.
18. Triassic Fishes of Connecticut: by Charles Rochester Eastman.
19. Echinoderms of Connecticut: by Wesley Roscoe Coe.
20. The Birds of Connecticut: by John Hall Sage and Louis Bennett Bishop, assisted by Walter Parks Bliss.
21. Fifth Biennial Report of the Commissioners of the State Geological and Natural History Survey, 1911-1912.
22. Guide to the Insects of Connecticut: prepared under the direction of Wilton Everett Britton. Part III. The Hymenoptera, or Wasp-like Insects, of Connecticut: by Henry Lorenz Viereck, with the collaboration of Alexander Dyer MacGillivray, Charles Thomas Brues, William Morton Wheeler, and Sievert Allen Rohwer.
23. Central Connecticut in the Geologic Past: by Joseph Barrell.
24. Triassic Life of the Connecticut Valley: by Richard Swann Lull.
25. Sixth Biennial Report of the Commissioners of the State Geological and Natural History Survey, 1913-1914.
26. The Arthrostraca of Connecticut: by Beverly Waugh Kunkel.
27. Seventh Biennial Report of the Commissioners of the State Geological and Natural History Survey, 1915-1916.
28. Eighth Biennial Report of the Commissioners of the State Geological and Natural History Survey, 1917-1918.
29. The Quaternary Geology of the New Haven Region, Connecticut: by Freeman Ward, Ph.D.
30. Drainage, Modification and Glaciation in the Danbury Region, Connecticut: by Ruth Sawyer Harvey, Ph.D.
31. Check List of the Insects of Connecticut: by Wilton Everett Britton, Ph.D. (In press.)

Bulletins 1, 9, 12, 17, 21, 25, 27, and 28 are merely administrative reports containing no scientific matter. The other bulletins may be classified as follows:

Geology: Bulletins 4, 6, 7, 8, 13, 18, 23, 24, 29, 36.

Botany: Bulletins 3, 5, 10, 11, 14, 15.

Zoölogy: Bulletins 2, 16, 19, 20, 22, 26, 31.

These bulletins are sold and otherwise distributed by the State Librarian. Postage, when bulletins are sent by mail, is as follows:

No.  1 $0.01      No. 13 $0.08      No. 23 $0.03  3 .08 14 .16 24 .10  4 .06 15 .06 25 .02  5 .03 16 .07 26 .06  7 .06 17 .02 27 .02  8 .05 18 .07 28 .02  9 .02 19 .08 29 .03 10 .08 20 .14 30 .03 11 .07 21 .02 31 12 .02 22 .08

The prices when the bulletins are sold are as follows, postpaid:

No.  1 $0.05      No. 13 $0.40      No. 23 $0.13  3 .10 14 .75 24 .65  4 .30 15 .35 25 .05  5 .15 16 .35 26 .80  7 .60 17 .05 27 .05  8 .20 18 .25 28 .05  9 .05

19 .45 29 .50 10 .35 20 .50 30 .45 11 .30 21 .05 31 12 .05 22 2.00

A part of the edition of these Bulletins have been assembled in volumes substantially bound in cloth, plainly lettered, and sell for the following prices, postpaid:

Volume      I,   containing Bulletins  1-5      $1.50 Volume      II,   containing Bulletins  6-12 2.45 Volume      III,   containing Bulletins  13-15 2.50 Volume      IV,   containing Bulletins  16-21 2.15 Volume      V,   containing Bulletin  22 2.50

It is intended to follow a liberal policy in gratuitously distributing these publications to public libraries, colleges, and scientific institutions, and to scientific men, teachers, and others who require particular bulletins for their work, especially to those who are citizens of Connecticut.

Applications or inquiries should be addressed to

George S. Godard,
State Librarian,
Hartford, Conn.

 

In addition to the bulletins above named, published by the State survey, attention is called to three publications of the United States Geological Survey prepared in co-operation with the Geological and Natural Survey of Connecticut. These are the following:

These papers may be obtained from the Director of the United States Geological Survey at Washington.

 

 

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CATALOGUE SLIPS.

 

Connecticut. State geological and natural history survey.

Bulletin no. 30. Drainage Modifications and Glaciation in the Danbury Region, Connecticut. By Ruth S. Harvey, Ph.D. Hartford, 1920.

59 pp., 5 pls., 10 fig., 25cm.

 

 

Harvey, Ruth Sawyer, Ph.D.

Drainage Modification and Glaciation in the Danbury Region, Connecticut. By Ruth S. Harvey, Ph.D. Hartford, 1920.

59 pp., 5 pls., 10 figs., 25cm.

 

Geology.

Harvey, Ruth S. Drainage Modifications and Glaciation in the Danbury Region, Connecticut. Hartford, 1920.

59 pp., 5 pls., 10 figs., 25cm.

 

 

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State Geological and Natural History Survey

COMMISSIONERS

Marcus H. Holcomb, Governor of Connecticut
Arthur Twining Hadley, President of Yale University
William Arnold Shanklin, President of Wesleyan University
Remsen Brickerhoff Ogilby, President of Trinity College
Charles Lewis Beach, President of Connecticut Agricultural College
Benjamin Tinkham Marshall, President of Connecticut College for Women

 

SUPERINTENDENT

Herbert E. Gregory

 

 

 

Publication Approved by the Board of Control

 

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CONTENTS.

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Page Introduction 9 Regional relations 11 Rocky River 15   Description of the river and its valley 15   Relation of the valley to geologic structure 16   Junction of Rocky and Housatonic Rivers 18

  Abnormal profile 18   Preglacial course 20   The buried channel 23   Effect of glaciation 25     The Neversink-Danbury valley 27     Still River 30   Statement of the problem 30   Evidence to be expected if Still River has been reversed 31     A valley wide throughout or broadening toward the south 32     Tributary valleys pointing upstream 34     The regional slope not in accord with the course of the Still 35     Evidence of glacial filling and degrading of the river bed 36     Glacial scouring 36   The Still-Saugatuck divide 38     Features of the Umpog valley 38     The preglacial divide 42   The Still-Croton divide 43     Introduction 43     Features of Still River valley west of Danbury 43     The Still-Croton valley 44     Glacial Lake Kanosha 45   Divides in the highlands south of Danbury 46   The ancient Still River 47   Departures of Still River from its preglacial channel 48     Suggested courses of Housatonic River 50     Glacial deposits 53     Beaver Brook Swamp 53     Deposits northeast of Danbury 54     Deposits between Beaver Brook Mountain and mouth of Still River 54     Lakes 55     History of the glacial deposits 56

 

 

 

ILLUSTRATIONS.

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Page PLATE I    View south on the Highland northeast of Neversink Pond 14   II A. View up the valley of Umpog

Creek 40     B. View down the valley of Umpog Creek 40   III    Limestone plain southwest of Danbury, in which are situated Lake Kanosha and the Danbury Fair Grounds 44   IV A. View down the Housatonic Valley from a point one-half mile below Stillriver Station 52     B. Part of the morainal ridge north of Danbury 52   V A. Kames in Still River valley west of Brookfield Junction 54     B. Till ridges on the western border of Still River valley, south of Brookfield 56 Page FIGURE 1. Present drainage of the Danbury region 13   2. Geological map of Still River valley 17   3. Profiles of present and preglacial Rocky River 19   4. Preglacial course of Rocky-Still River 21   5. Diagram showing lowest rock levels in Rocky River valley 24   6. Course of Still River 29   7. Map of Umpog Swamp and vicinity 39   8. Profiles of rivers 41   9. Early Stage of Rocky-Still River 49   10. Five suggested outlets of Housatonic River 51

 

 

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INTRODUCTION

The Danbury region of Connecticut presents many features of geographic and geologic interest. It may be regarded as a type area, for the history of its streams and the effects of glaciation are representative of those of the entire State. With this idea in mind, the field work on which this study is based included a traverse of each stream valley and an examination of minor features, as well as a consideration of the broader regional problems. Much detailed and local description, therefore, is included in the text.

The matter in the present bulletin formed the main theme of a thesis on "Drainage and Glaciation in the Central Housatonic Basin" which was submitted in partial fulfillment of the requirements for the degree of doctor of philosophy at Yale University.

The field work was done in 1907 and 1908 under the direction of Professor Herbert E. Gregory. I am also indebted to the late Professor Joseph Barrell and to Dr. Isaiah Bowman for helpful cooperation in the preparation of the original thesis, and to Dr. H. H. Robinson for assistance in preparing this paper for publication.

 

 

 

 

DRAINAGE MODIFICATIONS AND GLACIATION IN THE DANBURY REGION, CONNECTICUT

By Ruth S. Harvey

REGIONAL RELATIONS

The region discussed in this bulletin is situated in western Connecticut and is approximately 8 miles wide and 18 miles long in a north-south direction, as shown on fig. 1.[1] Throughout, the rocks are crystalline and include gneiss, schist, and marble--the metamorphosed equivalents of a large variety of ancient sedimentary and igneous rocks.

For the purposes of this report, the geologic history may be said to begin with the regional uplift which marked the close of the Mesozoic. By that time the mountains formed by Triassic and Jurassic folding and faulting had been worn down to a peneplain, now much dissected but still recognizable in the accordant level of the mountain tops.

Erosion during Cretaceous time resulted in the construction of a piedmont plain extending from an undetermined line 30 to 55 miles north of the present Connecticut shore to a point south of Long Island.[2] This plain is thought to have been built up of unconsolidated sands, clays, and gravels, the débris of the Jurassic mountains. Inland the material

consisted of river-made or land deposits; outwardly it merged into coastal plain deposits. When the plain was uplifted, these loose gravels were swept away. In New York, Pennsylvania, and New Jersey, however, portions of the Cretaceous deposits are still to be found. Such deposits are present, also, on the north shore of Long Island, and a well drilled at Barren Island on the south shore revealed not less than 500 feet of Cretaceous strata.[3] The existence of such thick deposits within 30 miles of the Connecticut shore and certain peculiarities in the drainage have led to the inference that the Cretaceous cover extended over the southern part of Connecticut.

A general uplift of the region brought this period of deposition to a close. As the peneplain, probably with a mantle of Cretaceous deposits, was raised to its present elevation, the larger streams kept pace with the uplift by incising their valleys. The position of the smaller streams, however, was greatly modified in the development of the new drainage system stimulated by the uplift. The modern drainage system may be assumed to have been at first consequent, that is, dependent for its direction on the slope of the uplifted plain, but it was not long before the effect of geologic structure began to make itself felt. In the time when all the region was near baselevel, the harder rocks had no advantage over the softer ones, and streams wandered where they pleased. But after uplift, the streams began to cut into the plain, and those flowing over limestone or schist deepened, then widened their valleys much faster than could the streams which flowed over the resistant granite and gneiss. By a system of stream piracy and shifting, similar to that which has taken place throughout the Newer Appalachians, the smaller streams in time became well adjusted to the structure. They are of the class called subsequents; on the other hand, the Housatonic, which dates at least from the beginning of the uplift if not from the earlier period of peneplanation, is an antecedent stream.

The complex rock surface of western Connecticut had reached a stage of mature dissection when the region was invaded by glaciers.[4] The ice sheet scraped off and redistributed the mantle of decayed rock which covered the surface and in places gouged out the bedrock. The resulting changes were of a minor order, for the main features of the landscape and the principal drainage lines were the same in preglacial time as they are today. It is thus seen that the history of the smaller streams like those considered in this report involves three factors: (1) the normal tendencies of stream development, (2) the influence of geologic structure, and (3) the effect of glaciation.

The cover of glacial deposits is generally thin, but marked variations exist. The fields are overspread with coarse till containing pebbles 6 inches in diameter to huge boulders of 12 feet or more. The abundance, size, and composition of the boulders in the till of a given locality is well represented by the stone fences which border fields.

 

 

 

 

The regional depression which marked the close of the glacial period slackened the speed of many rivers and caused them to deposit great quantities of modified or assorted drift. Since glacial time, these deposits have been dissected and formed into the terraces which are characteristic of the rivers of the region. A form of terrace even more common than the river-made terrace is the kame terrace found along borders of the lowlands. Eskers in the Danbury region have not the elongated snake-like form by which they are distinguished in some parts of the country, notably Maine; on the contrary, they are characteristically short and broad, many having numerous branches at the southern end like the distributaries of an aggrading river. The material of the eskers ranges from coarse sand to pebbles four inches in diameter, the average size being from one to two inches. No exposures were observed which showed a regular diminution in the coarseness of the material toward their southern end. The clean-washed esker gravels afford little encouragement to plant growth, and the rain water drains away rapidly through the porous gravel. Consequently, accumulations of stratified drift are commonly barren places. A desert vegetation of coarse grasses, a kind of wiry moss, and "everlastings" (Gnaphalius decurrens) are the principal growth. Rattlebox (Crotolaria sagittalis), steeplebush (Spiraea tomentosa), sweet fern (Comptonia asplenifolia), and on the more fertile eskers--especially on the lower, wetter part of the slope--golden rod, ox-eyed daisy, birch, and poplar are also present. All the eskers observed were found to be similar: they ranged in breadth across the top from 100 to 150 feet and the side slopes were about 20 degrees. Only a single heavily wooded esker was found, and this ran through a forest region.

The accumulations of stratified drift are distinguished from other features in the landscape by their smoother and rounder outlines, by their habit of lying unconformably on the bedrock without reference to old erosion lines, and by a slightly different tone in the color of the vegetation covering the water-laid material. The difference in color, which is due to the unique elements in the flora of these areas, may cause a hill of stratified drift in summer to present a lighter green color than that of surrounding hills of boulder clay or of the original rock slopes; in winter the piles of stratified drift stand out because of the uniform light tawny red of the dried grass.

 

glaciation is presumably Wisconsin. No definite indication of any older glacial deposits was found.

 

 

State Geol. Nat. Hist. Survey Bull. 30.  Plate I.

View south on the highland northeast of Neversink Pond. The base of a ridge in which rock is exposed is seen at the left; a crescent-shaped lateral moraine bordering the valley lies at the right.

 

 

 

 

ROCKY RIVER

DESCRIPTION OF THE RIVER AND ITS VALLEY

Rocky River begins its course as a rapid mountain brook in a rough highland, where the mantle of till in many places is insufficient to conceal the rock ledges (fig. 1). Near Sherman, about four miles from its source, it enters a broad flood plain and meanders over a flat, swampy floor which is somewhat encumbered with deposits of stratified drift and till. Rocky hills border the valley and rise abruptly from the lowland. The few tributaries of the river in this part of its course are normal in direction.

About six miles below Sherman, Rocky River enters Wood Creek Swamp, which is 5½ miles long by about one mile wide and completely covers the valley floor, extending even into tributary valleys. Within the swamp the river is joined by Squantz Pond Brook and Wood Creek. Tributaries to Wood Creek include Mountain Brook and the stream passing through Barses Pond and Neversink Pond. The head of Barses Pond is separated from the swamp only by a low ridge of till. Neversink Pond with its inlet gorge and its long southern tributary record significant drainage modifications, as described in the section entitled "The Neversink-Danbury Valley."

Within and along the margin of Wood Creek Swamp, also east of Wood Creek and at Barses Pond, are rounded, elongated ridges of till, some of which might be called drumlins. East of Neversink Pond is the lateral moraine shown in Pl. I. From the mouth of Wood Creek to Jerusalem, Rocky River is a quiet stream wandering between low banks through flat meadows, which are generally swampy almost to the foot of the bordering hills.

Near Jerusalem bridge two small branches enter Rocky River. Immediately north of the bridge is a level swampy area about one-half mile in length. Where the valley closes in again, bedrock is exposed near the stream, and beginning at a point one-half mile below (north of) Jerusalem, Rocky River--a swift torrent choked by boulders of great size--deserves its name. In spite of its rapid current, however, the river is unable to move these boulders, and for nearly three miles one can walk dry-shod on those that lie in midstream.

At two or three places below Jerusalem, in quiet reaches above rapids, the river has taken its first step toward making a flood plain by building tiny beaches. One-half mile above the mouth of the river the valley widens and on the gently rising south bank there are several well-marked terraces about three feet in height and shaped out of glacial material. A delta and group of small islands at the mouth of Rocky River indicate the transporting power of the stream and the relative weakness of the slow-moving Housatonic.

 

RELATIONS OF THE VALLEY TO GEOLOGIC STRUCTURE

Rocky River is classed with streams which are comformable to the rock structure. This conclusion rests largely on the analogy between Rocky River and other rivers of this region. The latter very commonly are located on belts of limestone, or limestone and schist, and their extension is along the strike. The interfluvial ridges are generally composed of the harder rocks. The valleys of the East Aspetuck and Womenshenuck Brook on the north side of the Housatonic, and of the Still, the Umpog, Beaver Brook, the upper Saugatuck, and part of Rocky River are on limestone beds (fig. 2). In the valleys between Town Hill and Spruce Mountain (south of Danbury), two ravines northwest of Grassy Plain (near Bethel), and the Saugatuck valley north of Umpawaug Pond, the limestone bed is largely buried under drift, talus, and organic deposits, but remnants which reveal the character of the valley floors have been found. The parallelism between the courses of these streams and that of Rocky River and the general resemblance in the form of their valleys, flat-floored with steep-sided walls, as well as the scattered outcrops of limestone in the valley, have led to the inference that Rocky River, like the others, is a subsequent stream developed on beds of weaker rock along lines of foliation.