BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA VoC. 42, PP. 467-480; 9 FIGS. JUNE 30. 1931 --------1----------------------------------------------------------------- 1--- KAMES AND KAME TERRACES OF CENTRAL MASSACHUSETTS 1 BY THOMAS C. BROWN (Head before the Geological Society December SO, 1930) CONTENTS Page Introduction ..................................................................................................................... 467 Location of the kames and kame terraces................................................................ 468 Jackson Avenue 420-foot terrace........................................................................ 468 Kame terrace near Whitmanville..................................................................... 470 Kame terrace west of Templeton..................................................................... 470 Kames of Millers River Valley near Orange................................................ 471 Boulder-bearing kames and terraces................................................................. 473 Terraces of the southern part'of Nashua Valley........................................ 473 Terraces of the North Nashua River V alley................................................ 475 Interpretation of kames and kame terraces............. ........................................... 475 Salisbury’s interpretation of the New Jersey kames................................. 475 Interpretation of Massachusetts kames and kame terraces...................... 475 Concentration of cobblestones on kame surfaces...................................... 476 Graphic illustration of the origin of kames.................................................. 477 Summary ................................. — . : .............................................................................. 478 I ntroduction The numerous valleys of north central Massachusetts are bordered by more or less continuous terraces at elevations varying from 200 feet above sealevel in the lower part of the Nashua Valley northeast of Pepperell to more than 1,000 feet in the upper reaches of Millers River Valley north of Winchendon. These terraces vary in areal extent from mere discon­ tinuous fringes in some of the valleys to broad sand plains a mile or more in width, such as the plains surrounded by the 260-foot contour south of Ayer and south and east of Shirley village; Many of these terraces have kames associated with them, either broad areas of knob-and-basin topog­ raphy like that of Bakers Brook Valley east of Fitchburg, or single scat- 1 Manuscript received by the Secretary of the Society January 5, 1931. (467) X X X — B u l l . G e o l . S o c . A m ., Vol.. 42, 1931. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/42/2/467/3430152/BUL42_2-0467.pdf by guest on 26 September 2021 468 T. C. BROWN---- KAMES AND KAME TERRACES OP MASSACHUSETTS tered hillocks jutting out into the valley like those along Millers River west of Orange. During the past few years extensive road and concrete construction has brought about the opening of numerous sand and gravel pits in these sand plains and kames. As a result fresh sections of the interior have been opened up on a scale that gives the geologist an unusual opportunity to study the structure of these deposits. From the scores of different pits studied in the past few years, a few typical cases are here selected for careful description, and an attempt is made to explain their origin. L o c a t io n o f t h e K a m e s a n d K a m e T e r r a c e s ■ JACKSON AVENUE 42O-FOOT TER RA C E Near the east end of Jackson Avenue, in the eastern part of Fitchburg, an extensive sand and gravel pit furnishes an excellent section of the 420- F ig u re 1.— Sand Pit near Jackson Avenue, east of Fitchburg This illustration shows a section in the terrace along the western side of Bakers Brook Valley. The top-set beds of coarse gravel are horizontal ; the sands and fine gravels beneath them are intricately cross-bedded. foot terrace on the west side of Bakers Brook. In this pit the working face is approximately 25 feet high. The upper 6 feet is composed of horizontally bedded coarse gravel with numerous pebbles and cobblestones 4 to 6 inches or more in diameter, all well rounded and fresh and nearly all of granite. Beneath this coarse gravel is at least 20 feet of intricately cross-bedded sands and fine gravels. Many of the beds are lens-shaped ; ^ others dip at variable angles and in various directions. These dipping beds are frequently truncated and covered by others that are practically Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/42/2/467/3430152/BUL42_2-0467.pdf by guest on 26 September 2021 LOCATION OP THE KAMES AND KÄME TERRACES 4 6 9 horizontal. Aside from the top bed of coarse gravel, no bed or series of beds shows any consistent or persistent dip in any direction for more than a few feet. In the same 420-foot terrace, about 200 yards south of this sand pit, another excellent section was exposed by an extensive piece of grading in the northern part of Saint Bernard’s Cemetery. In reducing one of the rather abrupt natural terrace slopes to more gentle contours, the whole upper surface over an area of a half-acre or more was excavated by steam shovel and moved down the grade. The part excavated was in some places as much as 15 feet in depth and 50 yards or more in length. Examina- F ig u re 2.— Section of Käme Terrace at Elevation of 820 feet, a Quarter of a Mile south of Whitmanville This exposure, which is in a road gravel pit, shows clearly that the original bedding has been disturbed by slumping toward the valley since deposition, and that the surface slope is due in part to the settling of the beds and not wholly to erosion. tions made at different times during the progress of this work showed that the structure of the sand plain here is identical with that of the sand pit farther north. The upper 4 feet or more is coarse horizontally-bedded gravel. Below this come cross-bedded sands and fine gravels, the sands predominating; the beds and lenses of material dip at comparatively low angles, but in almost every direction. There is no dominant direction of dip as in the fore-set beds of a delta; the bedding may better be com­ pared with that characteristic of kames, which has been graphically de­ scribed as “tumultuously bedded.” Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/42/2/467/3430152/BUL42_2-0467.pdf by guest on 26 September 2021 470 T. C. BROWN---- KAMES AND KAME TERRACES OF MASSACHUSETTS KA ME TERRACE HEAR WH1TMANVILLE A pit opened for road gravel in a kame terrace at an elevation of 820 feet, a quarter of a mile south of the bridge on the Whitmanville-Gardner road, exposes an excellent section of the terrace. Here again the upper beds are nearly horizontal and composed largely of coarse gravel, and the lower beds are sandy and irregularly cross-bedded. This pit was ex­ cavated to the valley margin, and shows clearly the internal structure where the terrace slopes down to join the valley floor (see figure 2) . The surface slope is due not to erosion, but largely to the slumping of the beds. This is clearly seen by following the massive bed of fine sand which F ig u re 3.— Terrace west of Templeton This structure seems to indicate that the terrace was built up to a uniform level with horizontal top-set beds. Then through some unknown cause a portion of the terrace slumped down and the sag was later filled with fore-set beds. is shown in horizontal position near the right side of the picture. About one-third of the way across the picture this bed is dropped vertically a foot or more by a normal fault; in the next third of the section it dips at a considerable angle; and in the last third it is so disturbed and mingled with material from the overlying bed of gravel that its identity is lost. Erosion may have modified the slope to some extent, but it could not cause this mingling of the beds. KAME TERRACE WEST OF TEMPLETON A sand pit opened during the construction of the State road through Templeton disclosed the structure shown in figure 3. This pit is one Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/42/2/467/3430152/BUL42_2-0467.pdf by guest on 26 September 2021 LOCATION OP THE KAMES AND KAME TERRACES 4 7 1 mile west of Templeton on the west side of Trout Brook and the south side of the State road, opposite the Templeton Cemetery. Only the upper part of the pit is shown in the figure. The arrangement of beds seems to indicate that this terrace was at one time built up to uniform level with horizontal top-set beds like those described in the previous examples but composed of finer material. Then these horizontal top-set beds sagged into the synclinal structure shown in the figure, and the sag was later filled with fore-set beds, bringing it once more to the terrace level. KAMES OF MILLERS RIVER VALLEY NEAR ORANGE On the north side of Millers Eiver, one mile west of Orange, is a kame at an elevation of 560 feet, having the structure shown in figure 4. This F ig u r e 4.— A Kame Ridge "beside the State Road one Mile west of Orange This illustration shows how the upper beds have slumped down the side of the kame and become crumpled and bent during the movement. kame is composed largely of fine sand. The crumpling of the beds, at first glance, suggests pressure due to ice movement, but a careful study of the kame in its natural setting shows th at this crumpling is more likely due to the removal of support and consequent slumping. Half a mile west of this kame, at the same elevation and on the north side of the river but the south side of the road, is the kame shown in figure 5.