Ground Water in the Norwalk, Suffield, and Glastonbury Areas, Connecticut

Windlass rig do No rig Nonfailing. Nonfailing. For assay see p. 158. Nonfailing. Do. Do. Do. Fails. Nonfailing. Aban- doned. Do. Nonfailing. Nonfailing. Aban- doned. Abandoned. Nonfailing. Nonfiiling. For analysis see p. 158. Nonfailing, Do. Do. Do. Do. NonfaiJing. For analysis see p. 158. NonfaiUng. Fails. Do. Nonfailing. Do. Do. Fails. Nonfailing. Do. Do. House destroyed. MARLBORO. 161 Wells duff in stratiflcd drift in Glastonbury — Continued. No. on PI. VI. O^sTier. Topo- graphic situation. g d c8 09 % O ^•3 •o j: ■^B ■S ex o. O <B ^ 0 P Feet. Feet. Feet. 12.5 5.3 7.2 19. .5 16.4 3.1 17.5 10.0 7.5 12.7 9.2 3.5 38.6 3.5.9 2.7 18.9 12.6 6.3 15.6 13.7 1.9 23.0 17.5 5.5 14.6 12.5 2.1 18.7 14.4 4.3 Rig. Remarks. 42 45 46 48 I 50 57 Jolui Vail. Albert L. Peck. 5g 59 'J!Vv."]3ailVy.' Valley... do... Plain do... Terrace . . do... .do. .do. .do. .do. Feet. 400 4tO 435 450 4,50 260 250 400 390 380 Chain pump . . . Windlass rig . . . Chain pump . . . Windlass rig. . . Two-buclcet rig. Windlass rig . . . Two-bucket rig. Windlass rig . . . House pump . . . Windlass rig . . . Nonfailing. Do. Nonfailing. For assiy see p. 158. Nonfailing. Fails. For assay see p.] 58. NonfaiUng. Fails. Drilled wells in Glastonbury. a oJ a o o a b, o S S • No. on PI. VI. Owner.. Topo- graphic situation. P. 1 5fe . 1 C8 Kind of rock. Remarks. w ^ O Q fi >■■ Feet. Feet. Feet. Feet. In. Gaits. 29 Herliert E. Mitchell Slope. .. 360 224 10 0 6 14 Sand- stone. Water flows from casing. 40 M. R. Tryoa ...do....| 430 64 12 10 6 12 ...do.. MARLBORO. AREA, POPULATION, AND INDUSTRIES. Marlboro is a small highland farming town in the southeast corner of Hartford County. It is 10 miles east of Middletown and 15 miles southeast of Hartford. The town has an area of 23 square miles, of which four-fifths is wooded. The town keeps in condition about 40 miles of roads, and there are in addition 7 miles of roads which have been discontinued. Eventually the State trunk line be- tween Hartford and New London wall run through the town. There are stations of the Air Line division of the New York, New Haven & Hartford Railroad at East Hampton and Lyman Viaduct. Marl- boro, a rather straggling village, is the only settlement. In 1803 the town was organized, about 4 square miles of territory being taken from Glastonbury, 9 from Hebron, and 9 from Colchester. In 1813 1| square miles more was annexed from Glastonbury/ In 1910 the population w^as 302, a decrease of 20 from the population in 1900. This is equivalent to a density of population of 13 inhabitants to the 154444*^ Hall, Mary, Marlboro, Conn., from 1736 to 1903, p. 34. -20 11 162 CtEound water iisr nor walk and other areas, conn. square mile. Marlboro has the sraallest population of the towns in the State, and only one other town has a lower density of population. In general there has been a very decided decrease in population. In the first half of the nineteenth century there was some manufacture of cotton cloth for shipment to the South, but this ceased during the Civil War and was never revived. About 1885 a mill was built for the manufacture of silk, especially ribbon, and a number of work- men were brought in, but this enterprise was not long lived. The changes in population shown in the following table reflect the vary- ing prosperity of the mills and the general tendency to move from farms to manufacturing centers : Population of Marlboro, 1810-1910.'' Year. Popula- tion. Per cent change. Year. Popula- tion. Percent change. 1810 720 839 704 713 832 682 1870 476 391 582 322 302 -30 1820 + \7 -16 -1- 1 + 17 -18 1880 -18 1830 1890 -i-49 1840 1900 —45 1850 1910 - 6 1880.. . . a Connecticut Register and Manual, 1919, p. 639. At present the principal industry is mixed agriculture. There is also considerable charcoal burning and production of native lumber. SURFACE features. Marlboro lies in a thoroughlj^ dissected plateau region. The hilltops range in elevation from 500 feet above sea level in the south part of the town to 700 feet in the north. They are remnants of a flat surface below which the streams have cut deep valleys, and most of tliem are in the form of ridges elongated in a north- south direction. Their direction is not dependent on the rock struc- ture but is rather the result of the original direction of the streams. There are several points about 720 feet above sea level, the greatest elevation in Marlboro. The lowest point is where Blockledge River crosses the Colchester toAvn line at an elevation of 200 feet above sea level. Dickinson Creek, Blockledge River, and Fawn Brook and their tributaries drain Marlboro. They are all tributary to Salmon River, which enters Connecticut River at East Haddam. water-bearing formations. Three types of bedrock have been recognized by Gregory ^ in JSIarlboro — the Bolton schist, Maromas granite gneiss, and Hebron * Gregory, II. E., and Robinson, H. H., Preliminary Connecticut Geol. and Nat. Hist. Survey Bull. 7, 1907. geological map of Connecticut : MARLBORO. 163 pieiss. The unconsolidated mantle rocks include till and stratified drift. The former is the most important source of <)fround water in the town. xSV7^isY and gneiss. — The Bolton schist underlies an area of a quarter of a square mile in the west corner of Marlboro where it borders on East Hampton and Glastonbury. It is a fairly typical mica schist composed of granules of quartz and feldspar in large part surrounded and enwrapped by flakes of mica. The mica flakes, by reason of their cleavability and roughly parallel arrangement, give the rock its fissile character, and they also give it a gray color with something of a silvery luster. The Maromas granite gneiss underlies a northward-striking belt of country a mile wide adjoining the Bolton schist area and west of Marlboro Pond. This rock is of variable character, but typically it is a biotite gneiss composed essentiallj- of quartz, feldspar, and biotite (black mica) wath small amounts of accessory minerals. Its boundary against the Bolton schist is not sharp, for it sends stringers into the schist. The Hebron gneiss, which underlies about 85 per cent of the area of the town, according to Gregory,^ '• varies from a granitic gneiss to highly fissile schist."" On one side it grades into a true gneiss and on the other into schists. These rocks are to all intents and purposes alike as far as their ability to carry water is concerned. The stresses which metamor- phosed them also made many cracks and joints. Water which falls as rain is in part absorbed by the overlying unconsolidated till and stratified drift. Some of this water is slowly transmitted to the net- work of interconnecting joints, through which it circulates under gravity, and it may be recovered by means of drilled wells. A hole drilled into these rocks at anj^ point will probably cut one or more of these water-bearing fissures and so procure a supply of water adequate in abundance and reliability for ordinary domestic and farm needs. Till, — Till overlies the bedrock of Marlboro, except for the numer- ous small areas of actual rock outcrop and an area of stratified drift in a valley northwest of Marlboro Pond. (See map, PL YII.) It forms a mantle that is in general 10 to 40 feet thick and is. com- posed of all the debris plucked and ground along beneath the ice. Pebbles, cobbles, and boulders of great and small size are embedded in a matrix of tightl}- packed sand, silt, clay, and fine rock flour. The constituent particles are in large part angular, so that they inter- lock and bind one another together. Much of the till is in conse- quence very dense and tough, as is indicated by the name " hardpan " * Rice, W. N., and Gregory. H. E., Manual of the geology of Connecticut : Connecticut Oeol. and Nat. Hist. Survey Bull. 6, p. 141, 1906. 164 GROUND WATER* IN NOR WALK AND OTHER AREAS, CONN. that is often applied to it. It has a moderate porosity and is able to absorb and transmit considerable water. The water is most abundant in the zone immediately overlying the bedrock and in a few widely scattered lenses of partly washed and roughly stratified ma- terial within the till. Wells dug into the till to a depth below the lowest level reached by the top of the saturated zone in times of drought will procure satisfactory supplies of water. Measurements were made of 31 such wells in Marlboro in September, 1916. Of these wells 19 were said to be nonf ailing and 7 were said to fail ; the reliability of the remaining 5 wells was not ascertained. The fol- lowing table summarizes the data collected concerning the depths of these 31 wells : Summary of roells dug in till in MarJhoro. Maximum Minimum . Average. . Total depth. Depth to water. Feet. 29.2 8.7 15.7 . Feet. 21.5 4.1 in. 7 i Depth of water in well. Feet. 16.8 1.6 5.0 QUALITY OF GROUND WATER. The accompanying table gives the results of two analyses and three assays of samples of ground water collected in the town of Marlboro. The waters are low in mineral content, except Nos. 19 and 26, which are moderately mineralized. Nos. 12 and 27 are very soft, Xo. 23 is soft, and Nos. 19 and 26 are comparatively hard. All are accept- able for domestic use in so far as this may be determined by a chem- ical investigation of their mineral content. Nos. 12 and 27 are suit- able for boiler use, but the other three are rated fair for boiler use be- cause they contain considerable amounts of scale-forming ingredi- ents. No. 19, moreover, is liable to cause a little trouble by foaming. Nos. 12 and 27 are sodium-carbonate waters : Nos. 23 and 26 ai'e cal- cium-carbonate in type; and No. 19 is classed as a sodium-chloride water. MARLBORO. 166 Vhcuiiftrl roiti position and rla-^sification of [rround xntcrs in Marlboro.'^ [Parts per million. Collected Dec. 5, 1916; analyzed by Alfred A. Chambers and V. FT. Kidwell. Numbers of analyses and assays correspond to those used on Pi. VI.] SlUca (SiOs) Iron(Fe)