Chapter IV: Introduction

The deep valley extending from the Danbury Fair Grounds to the East Branch Reservoir in the Croton River system, has given rise to the suggestion that the course of the Housatonic formerly may have been along the line of Still and Croton rivers and thence to the Hudson.[11] From the evidence of the topographic map alone, this hypothesis appears improbable. The trend of the larger streams in western Connecticut is to the south and southeast; a southwesterly course, therefore, would be out of harmony with the prevailing direction of drainage. Also, the distance from the present mouth of Still River to tidewater by the Still-Croton route is longer than the present route by way of the Housatonic.

[Footnote 11: Hobbs, W. H., Still rivers of western Connecticut: Bull.
Geol. Soc. Am., vol. 13, p. 25, 1901.]

FEATURES OF STILL RIVER VALLEY WEST OF DANBURY

From Danbury to its source Still River occupies a valley whose features are significant in the history of the drainage. Between Danbury and the Fair Grounds (fig. 1) the valley is a V-shaped ravine 1-1/2 miles long, well proportioned to the small stream now occupying it but entirely too narrow for the channel of a large river. Along the valley are outcrops of schist, and granite rock is present on both sides of the valley for a distance of about one-quarter mile. Part of the valley is a mere cleft cut in the rock and is unglaciated. At the Danbury Fair Grounds the valley opens out into a marshy plain, through which the river meanders and receives two tributaries from the south. The plain, which extends beyond Lake Kanosha on the west, has a generally level surface but is diversified in places by mounds of stratified drift.

Near the railroad a rock outcrop was found which gives a clue to the nature of the broad lowland. The rock consists mainly of schist, but on the side next the valley there is a facing of rotten limestone. This plain, like all the others in this region, is a local peneplain developed on soluble limestone. A better example could not be found to prove the fallacy of the saying that "a broad valley proves the existence of a large river." The plain is simply a local expansion of a valley which on each side is much narrower. No other river than the one flowing through it can have been responsible for the erosion, for the plain is enclosed by hills of gneiss and schist (Pl. III).

At Mill Plain the valley is crowded by ragged rock outcrops which jut into the lowland. Here the river occupies a ravine cut in till near the north side of the valley. West of Mill Plain station the valley is encumbered with ridges of stratified drift, interspersed with heavy accumulations of till. Near Andrew Pond the true width of the valley--one-eighth mile--is shown by rock outcrops on both the north and south slopes. The valley at this point gives no indication of narrowing toward the headwaters; in fact, it becomes broader toward the west.

Between Andrew Pond and Haines' Pond is the divide which separates the waters of the Still system from those of the Croton. It consists of a jumbled mass of morainal hills, seemingly of boulder clay, that rise from 50 to 60 feet above the level of the ponds. The divide is thus merely a local obstruction in what was formerly a through drainage channel.

THE STILL-CROTON VALLEY

It is evident that before the advent of the glacier a stream must have flowed through the Still-Croton valley past the present divide in order to have excavated the rock valley there found. The Housatonic could not have flowed west through this valley if it was as narrow and shallow as is indicated by known rock outcrops; the river could have flowed through it only in a deep narrow gorge which was later buried under drift, but the evidence at hand does not support this view.

It is most probable that this valley was made by the preglacial Croton River. This explanation demands no change in the direction of Still and Croton Rivers but calls for a divide at some point east of the present one. From a divide between the Fair Grounds and Danbury, a small stream may be supposed to have flowed toward the east, joining the larger northern branch of the Still at a point near the middle of the city of Danbury. The stream flowing westward from this divide formed the headwaters of one branch of the Croton system.

The presence of till in a ravine can be used as a criterion for locating the site of a former divide, for where till is present in the bed of a stream the channel is of preglacial date. Where the river crosses a divide it should be cutting through rock, though till may be present on the valley slopes. Judged by this test, the old divide was situated either just east of the Fair Grounds plain or at the east end of the ravine described in the preceding topic. Of these two positions the one near the Fair Grounds seems the more likely (fig. 1), for at this place the river has excavated a recent channel with steep sides in gneissoid rock. The absence of the limestone at this point may be sufficient in itself to explain the location of the divide.

Exact measurements of the drift in the upper Still valley are needed in order to establish this hypothesis completely and to plot the old channel, but the position of the rock floor of the former channel extending westward from the Fair Grounds may be fixed approximately. The rock at the assumed divide now stands at 420 feet above sea-level and it is reasonable to assume that ten feet has been removed by glacial scouring and postglacial erosion, making the original elevation 430 feet. The present divide between Andrew Pond and Haines' Pond has an elevation of 460, but the bedrock at this place is buried under 60 feet of drift, so that the valley floor lies at 400 feet. According to these estimates the stream which headed east of the Fair Grounds had a fall of 30 feet before reaching the site of the present Haines' Pond (fig. 8, B).

GLACIAL LAKE KANOSHA

When the Croton Branch was beheaded by drift choking up its valley west of Andrew Pond, the ponded waters rose to a height of from 20 to 30 feet and then overflowed the basin on the side toward Danbury. The outlet was established across the old divide, and as the gorge by which the water escaped was cut down, the level of the ponded waters was lowered. At the same time, also, the lake was filled by debris washed into it from the surrounding slopes. Thus the present flat plain was formed and the old valley floor, a local peneplain developed on the limestone, was hidden.

DIVIDES IN THE HIGHLANDS SOUTH OF DANBURY

The mountain mass to the south and southwest of Danbury, including Town Hill and Spruce, Moses, and Thomas mountains, is traversed by a series of parallel gorges trending nearly north and south (fig. 2). About midway in each valley is a col, separating north and south-flowing streams. Two of the valleys, those between Spruce and Moses mountains, and Thomas Mountain and Town Hill, form fairly low and broad passes. They were examined to see whether either could have afforded a southerly outlet for Still River.

The rock composing the mountains is granite-gneiss and schist with an average strike of N 30 deg. W, or very nearly in line with the trend of the valleys. The gneiss was found to be characteristic of the high ridges and schist to be more common in the valleys. No outcrops of limestone were found on the ridges, but at two or three localities limestone in place was found on low ground. From the facts observed it is evident that the stronger features of the relief are due to the presence of bodies of resistant rock, whereas the valleys are due to the presence of softer rock. The series of deep parallel valleys is attributed to the presence of limestone rather than schist.

The gorge between Spruce and Moses mountains, locally called "Sugar Hollow," narrows southward as it rises to the col, and the rock floor is buried under till and stratified drift to depths of 25 to 50 feet. Nevertheless it is probable that the valley was no deeper in preglacial time than it is now. The plan of the valley with its broad mouth to the north favored glacial scour so that the ice widened and deepened the valley and gave it a U form. Scouring and filling are believed to have been about equal in amount, and the present height of the divide, about 470 feet, may be taken as the preglacial elevation. This is 70 feet higher than the rock floor of the divide at West Redding. The pass could not, therefore, have served as an outlet for Still River.

The valley west of Town Hill is similar in form and origin to Sugar Hollow. The water parting occurs in a swamp, from each end of which a small brook flows. The height of the pass in this valley--590 feet-- precludes its use as an ancient outlet for Still River. Likewise the valley east of Town Hill affords no evidence of occupation by a southward through-flowing stream.

THE ANCIENT STILL RIVER

The conclusion that the Still-Umpog was not reversed by a glacial dam does not preclude the possibility that this valley has been occupied by a south-flowing stream. It is probable that in an early stage in the development of the drainage, the streams of the Danbury region reached Long Island Sound by way of the Still-Umpog-Saugatuck valley. Along this route, as described under the heading "The Still-Saugatuck Divide," is a fairly broad continuous valley at a higher level than the beds of the present rivers. A south-flowing river, as shown in fig. 9, brings all the drainage between Danbury and the Housatonic into normal relations.

This early relationship of the streams was disturbed by the reversal of the waters of the ancient Still in the natural development of a subsequent drainage. The Housatonic lowered the northern end of the limestone belt, in the region between New Milford and Stillriver village, faster than the smaller south-flowing stream was able to erode its bed. Eventually a small tributary of the Housatonic captured the headwaters of the south-flowing river, and by the time the latter had been reversed as far south as the present divide at Umpog Swamp, it is probable that the advantage gained by the more rapid erosion of the Housatonic was offset by the Saugatuck's shorter course to the sea. As a result the divide between Still and Saugatuck Rivers at Umpog Swamp had become practically stationary before the advent of the glacier.

The complex history of Still River is not fully shown in the stream profile, for the latter is nearly normal, except in the rock basins in the valley of the Umpog. This is due to the fact that changes in the course of the Still, caused by the development of a subsequent drainage through differential erosion, were made so long ago that evidence of them has been largely destroyed.

The foregoing conclusion practically eliminates hypothesis IV--that the Still developed from the beginning as a subsequent stream in the direction in which it now flows. This hypothesis holds good only for the short portion of the lower course of the present river, that is, the part representing the short tributary of the Housatonic which captured and reversed the original Still.

DEPARTURES OF STILL RIVER FROM ITS PREGLACIAL CHANNEL

Between Danbury and Beaver Brook Mountain the Still departs widely from its former channel, as shown in fig. 6. At the foot of Liberty Street in Danbury the river makes a sharp turn to the southeast, flows through a flat plain, and for some distance follows the limestone valley of the Umpog, meeting the latter stream in a swampy meadow. It then cuts across the western end of Shelter Rock in a gorge-like valley not over 200 feet wide. Outcrops of a gneissoid schist on the valley sides and rapids in the stream bear witness to the youthfulness of this portion of the river channel.

An open valley which extends from the foot of Liberty Street in a northeasterly direction (the railroad follows it) marks the former course of Still River, but after the stream was forced out of this course and superimposed across the end of Shelter Rock by the accumulation of drift in the central and northern parts of the valley, it was unable to regain its old channel until near Beaver Brook Mountain. The deposits of drift not only have kept the Still confined to the eastern side of its valley but have forced a tributary from the west to flow along the edge of the valley for a mile before it joins its master stream.

About a mile north of Brookfield Junction, Still River valley begins to narrow, and at Brookfield the river, here crowded to the extreme eastern side, is cutting a gorge through limestone. The preglacial course of the Still in the Brookfield region seems to have been near the center of the valley where it was joined by Long Brook and other short, direct streams draining the hillsides. The glacier, however, left a thick blanket of drift in the middle of the valley which turned the Still to the east over rock and forced Long Brook to flow for more than a mile along the extreme western side of the valley.

The broad valley through which the Still flows in the lower part of its course extends northward beyond it for over two miles, bordering the Housatonic River. At Lanesville near the mouth of the Still, the river has cut a gorge 30 feet deep and one-quarter mile long in the limestone. Upstream from this gorge the river meanders widely in a flat valley, whereas on the downstream side it has cut a deep channel in the drift in order to reach the level of the Housatonic. There is room in the drift-covered plain to the west for a buried channel of Still River which could join the Housatonic at any point between New Milford and Stillriver station. If the depth of the drift be taken at 25 feet, there would seem to be no objection to the supposition that the Still initially joined its master stream opposite New Milford, as shown in fig 6. After the limestone had been worn down to approximate baselevel, the tendency of the Still would have been to seek an outlet farther south in order to shorten its course and reach a lower level on the Housatonic. This stage in the evolution of the river may not have been reached before the ice age, and it is thus possible that glacial deposits may have pushed the river to the extreme southern side of its valley, superimposed it over rock, and forced it to cut its way down to grade.

SUGGESTED COURSES OF HOUSATONIC RIVER

As possible former outlets for the Housatonic, Hobbs has suggested the Still-Umpog-Saugatuck valley or the Still-Croton valley (by way of the East Branch Reservoir)[12], whereas Crosby has suggested the Ten Mile-Swamp River-Muddy Brook-Croton River valley (by way of Webatuck, Wing's Station, and Pawling), or the Fall's Village-Limerock-Sharon- Webatuck Creek-Ten Mile valley.[13] The sketch map, fig. 10, indicates the courses just outlined and one other by way of the Norwalk. The latter is the route followed by the Danbury and Norwalk Division of the Housatonic Railroad. It is natural to assume that the Housatonic might have occupied anyone of these lines of valleys, particularly where they are developed on limestone and seem too broad for the streams now occupying them. Nevertheless, although each of these routes is on soft rock and some give shorter distances to the sea than the present course, it is highly improbable that the Housatonic ever occupied any of these valleys. For had the river once become located in a path of least resistance, such as is furnished by any of these suggested routes, it could not have been dislodged and forced to cut its way for 25 miles through a massive granitic formation, as it does between Still River and Derby, without great difficulty (Pl. IV, A).

An inspection of the larger river systems of Connecticut shows that the streams composing them exhibit two main trends. Likewise, the courses, of the larger rivers themselves, whether trunk streams or tributaries, combine these two trends, one of which is northwest-southeast and the other nearly north-south.

The north-south drainage lines are the result of geologic structure, and many broad, flat-floored valleys, often apparently out of proportion to the streams occupying them, have this direction. On the other hand, the northwest-southeast drainage lines across the strike of formations, coincide with the slope toward the sea of the uplifted peneplain whose dissected surface is represented by the crests of the uplands. The valleys of streams with this trend are generally narrow, and some are gorges where resistant rock masses are crossed. The northwest-southeast trends of master streams thus were determined initially by the slope of the peneplain, whereas the north-south trends represent later adjustments to structure.

It is concluded, therefore, that the Housatonic between Bulls' Bridge and Derby (fig. 10), had its course determined by the slope of the uplifted peneplain and is antecedent in origin. The old headwaters extended northwest from the turn in the river near Bull's Bridge, whereas that part of the river above Bull's Bridge was initially a minor tributary. This tributary, because of its favorable situation, in time captured all the drainage of the extensive limestone belt to the north and then became part of the main stream. The lower Housatonic, therefore, has always maintained its ancient course diagonal to the strike of formations, and differential erosion, which reaches its maximum expression in limestone areas, is responsible for the impression that the Still River lowland and other valleys west of the Housatonic may once have been occupied by the latter stream.

[Footnote 12: Hobbs, W. H., Still rivers of western Connecticut: Bull.
Geol. Soc. Am., vol. 13, p. 25, 1901.]

[Footnote 13: Crosby, W. O., Notes on the geology of the sites of the
proposed dams in the valleys of the Housatonic and Ten Mile rivers:
Tech. Quart., vol. 13, p. 120, 1900.]

GLACIAL DEPOSITS

BEAVER BROOK SWAMP

A broad belt of limestone extends along the eastern side of the granite ridge of Shelter Rock and in preglacial time formed a broad-bottomed valley whose master stream had reached old age. When the glacier came it hampered the drainage by scooping out the rock bottom of the valley in places and by dropping deposits at the mouth of Beaver Brook valley, thus forming Beaver Brook Swamp or "The Flat," as it is called (fig. 6).

Among the deposits at the southern end of Beaver Brook Swamp is considerable stratified drift in the form of smoothly rounded hills or kames, which are situated both on the border of the valley and in the swamp. Till containing medium-sized boulders of granodiorite-gneiss occurs along the road which borders the east side of the densely wooded swamp.

Along the northeastern border of the swamp is a flat-topped terrace of till, perhaps a lateral moraine, through which a small stream heading to the north has cut a V-shaped ravine. A lobe of fine till extends into the valley from the northeast and narrows the outlet.

Between the railroad and highway, which cross the northern end of the swamp, is an irregular wooded eminence of rock, partly concealed by a veneer of drift. Between this knoll and Shelter Rock are heavy deposits of sand in the form of a short, broad terrace with lobes which point into the Still River valley. A similar terrace is found to the northwest on the opposite side of the valley.

At the northern end of Shelter Rock along the blind road leading to the summit is a peninsula-like body of drift which contains huge granite boulders mixed here and there with pockets of sand and gravel. Stratified drift was found at the foot of the hill, and till overlying it higher up. The more usual arrangement is boulder clay overlain by modified drift, the first being laid down by the ice itself, the second being deposited by streams from the melting glacier in its retreat. Huge boulders, many ten feet or more in diameter, are strewn over the northern slope of Shelter Rock.

DEPOSITS NORTHEAST OF DANBURY

North of the railroad, opposite Shelter Rock (fig. 6), is a most interesting flat-topped ridge of drift which topographically is an extension of the higher rock mass to the northwest. In this drift mass are to be found in miniature a number of the forms characteristic of glacial topography. The broad-topped gravel ridge slopes sharply on the north into a flat-bottomed ravine which is evidently part of the Still River lowland. This portion of the valley has been shut off by drift deposits. The drainage has been so obstructed that the stream in the ravine turns northeast away from its natural outlet. In the valley of "X" brook (fig. 1) are terraces, esker-like lobes, and detached mounds of stratified drift resting on a foundation of till.

Along the eastern border of the hill is to be seen the contact between two forms of glacial deposits (Pl. IV, B). A mass of stratified drift overlies a hummocky deposit of coarse till, but large boulders occurring here and there on top of the stratified drift show that the ice-laid and water-laid materials were not completely sorted. Boulders seem to have been dropping out of the ice at the same time that gravel was being deposited. Boulders of granite-gneiss eight feet or more in diameter, carried by the ice from the hills to the north and northeast, are strewn at the foot of the hill.

DEPOSITS BETWEEN BEAVER BROOK MOUNTAIN AND MOUTH OF STILL RIVER

About a mile beyond Beaver Brook Mountain, the railroad cuts through the edge of a hill 80 feet in height exposing a section consisting of distinctly stratified layers of fine white quartz sand, coarser yellowish sand, and small round pebbles. The quartz sand was used at one time in making glass. Farther east where the two tracks of the New York and New England railroads converge, a cut shows a section of at least 40 feet of boulder clay. Near the river, limestone boulders are common, indicating that the valley to the north was degraded to some extent by the glacier.

In the valley at Brookfield Junction and on its western side, are thick deposits of clean sand. One mile north of Brookfield Junction, along the western border of the valley, an esker follows an irregular course for several hundred yards approximately parallel to the river and terminates at its southern end in a group of kames (Pl. V, A and B). Opposite the point where these accumulations occur, is a terrace-like deposit of till. Between the gorge at Brookfield and the mouth of Still River, swampy areas, flat meadows, and small hills of drift occur.

In comparison with the Still River lowland, the flat land east of Green Mountain may be called a plateau. The step between the two is made by an east-facing rocky slope, the outline of which has been softened by a lateral moraine separated from the plateau edge by a small ravine. On the lowland below the moraine is a group of kames. Near Lanesville (fig. 6), are thick deposits of water-laid material, including a hill of gravel near the river having a large bowl-shaped depression on one side formed by the melting of an ice block. Two and a half miles south of Lanesville on the west side of the lowland, a wooded esker extends for about one-quarter mile parallel to the valley axis and then merges into the rocky hillside.

LAKES

The lakes of this region are of two kinds: (1) those due to the damming of river valleys by glacial deposits and (2) rock basins gouged out by the ice.

Among the lakes which owe their origin to drift accumulations in the valleys are Andrew and Haines' ponds at the head of Still River. These are properly parts of the Croton River system, but Andrew Pond has been held back by the deep filling of boulder clay in the valley. Lake Kanosha, in the same valley, is a shallow lake formed in the drift. The lake south of Spruce Mountain at the head of the Saugatuck seems to be enclosed by drift alone.

Neversink Pond, Barses Pond, Creek Pond, and Leonard Pond are the remnants of larger water bodies now converted into swamps. Squantz Pond and Hatch Pond have dams of drift. Eureka Lake and East Lake appear to be rock basins whose levels have been raised somewhat by dams of till. Great Mountain Pond and Green's Pond, between Great Mountain and Green Mountain, are surrounded by rock and their level has been raised several feet by artificial dams. Great Mountain Pond is at least 50 feet above the level of Green Pond and separated from it by a rock ridge (fig. 2).

HISTORY OF THE GLACIAL DEPOSITS

A tongue of the glacier is supposed to have lain in the valley of the Umpog and gradually retreated northward after the ice had disappeared from the uplands on either side. The ridge of intermediate height built of limestone and schist, which extends down the middle of the valley, was probably covered by ice for some time after the glacier had left the highlands.

When the mountain mass extending from Pine Mountain to Town Hill west of the Umpog Basin and the granite hills to the east terminating in Shelter Rock are considered in their relation to the movement of the ice, it is apparent that the valley of the Umpog must have been the most direct and lowest outlet for glacial streams south of Danbury. These streams built up the terraces and other deposits of stratified drift which occupy the valley between Bethel and West Redding.

The heavy deposits of till near West Redding mark a halt in the retreating glacier. The boulders at this point are large and numerous, and kames and gravel ridges were formed. The deposits at the divide, supposed to have formed a glacial dam which reversed the Umpog,[14] are much less heavy than at points short distances north and south of the water parting.

As the ice retreated, sand and gravel in the form of terraces accumulated along the margin of the Umpog valley, where the drainage was concentrated in the spaces left by the melting of the ice lobe from the hillside. Among these deposits are the bodies of sand and gravel which lie against the rocky hillslopes most of the way from the Umpog-Saugatuck divide to Bethel. North of Bethel, the drainage seems to have been gathered chiefly in streams flowing on each side of the low ridge occupying the center of the valley; consequently the gravel was deposited along the sides and southern end of the ridge and in the sag which cuts across its northern end. The row of kames at the north end of Umpog Swamp, several knolls of drift in Bethel, and the kame-like deposits and esker north of Grassy Plain were laid down successively as the ice retreated down the valley. During this period, the drainage was ponded between the ice front and the Umpog-Saugatuck divide.

Uncovering the Still-Croton valley did not give the glacial drainage any lower outlet than the Umpog-Saugatuck divide afforded (fig. 8, B and C.)

The heavy deposits of boulder clay forming the moraine which blocks the Rocky River valley indicate the next halting place of the glacier. In this period the ice margin formed an irregular northeast-southwest line about a mile north of Danbury. The country west and south of Danbury was thus uncovered, but the lower part of Still River valley was either covered by the ice sheet or occupied by an ice lobe. The drainage was, therefore, up the river valley, and being concentrated along the valley sides resulted in the accumulation of sand and gravel at the foot of rocky slopes. It is possible that an ice lobe extended down the old Rocky River valley, perhaps occupying much of the country between Beaver Brook Mountain and the high ridge west of the valley. The streams issuing from this part of the ice front would have laid down the eskers and kame gravels north of Danbury and the thick mantle of drift over which Still River flows through the city. As would be expected, this accumulation of material ponded all the north-flowing streams--Umpog Creek, Beaver Brook, and smaller nameless ones--and at the same time pushed Still River, at its mouth, to the southern side of its valley. Beaver Brook valley, Umpog valley, and all the Danbury basin must have been flooded during this period up to the height of the "railroad divide." Within the area covered by the city, the valley was filled up to at least 70 feet and probably much more than that above its former level. Flowing at this higher level, the river was thrown out of its course and here and there superimposed on hard rock--as, for example, at Shelter Rock.

That part of the drainage coming down the valley opposite Beaver Brook met the drainage from Still River ice lobe in the valley north of Shelter Rock, and as a result heavy deposits of stratified drift were laid down. The peninsula-like mass of drift beyond the river north of Shelter Rock appears from its form to have been built up as the delta of southward and eastward-flowing streams; probably the drainage from the hilltops united with streams coming down the two valleys. The lobes of stratified drift extending from the ridge may have been built first, and later the connecting ridge of gravel which forms the top of the hill may have accumulated as additional material was washed in, tying together the ridges of gravel along their western ends. The mingling in this region of stratified drift of all grades of coarseness indicates the union in the same basin of debris gathered from several sources.

Between Danbury and New Milford no moraine crosses either the Rocky or the Still valley, but the abundance of till which overspreads the whole country indicates a slowly retreating glacier well loaded with rock debris. The mounds of stratified drift scattered along the valley doubtless represent the deltas of streams issuing from the ice front. The waters of Rocky River were ponded until the outlet near Jerusalem was uncovered and the disappearance of ice from the ravine below allowed an escape to the Housatonic. Stratified drift is present in greatest amount along the valleys of Still River and the west fork of Rocky River, indicating that these were the two chief lines of drainage. The uplands are practically without stratified drift.

Along the valley of the Housatonic, glacial material is chiefly in the form of gravel terraces; they extend from Gaylordsville to New Milford, in some places on one side only, in others on both sides of the river. Part of these gravel benches are kame terraces, as shown by their rolling tops and the ravine which separates the terrace from the hillside; others may have been made by the river cutting through the mantle of drift which was laid down in the period of land depression at the time of glacial retreat,[15] or they may be a combination of the two forms. In many places by swinging in its flood plain, the river has cut into the terraces and left steep bluffs of gravel. The valley of Womenshenuck Brook above Merwinsville contains heavy deposits of stratified drift, indicating that this broad valley which extends from Kent on the Housatonic to Merwinsville was an important channel for the water which flowed from the melting ice.

[Footnote 14: Rice, W. N. and Gregory, H. E., Manual of the Geology of
Connecticut: Conn. Geol. and Nat. Hist. Survey Bull. 6, pp. 34-35,
1906.]

[Footnote 15: Hobbs, W. H., op. cit.]

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Transcriber's Notes:

With the following exceptions, the text presented here is that obtained through scanned images from an original copy of the manuscript.

Possible Typographic Errors Corrected
occuying => occupying
PLATE II A. "of" repeated

Emphasis Notation:
_text_ - italicized
=text= - bold
~text~ - small caps