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Home , Geology of New Hampshire, Glacial striation, Mount Crescent

Surficial Geology of the Jefferson 7.5' Quadrangle,

71°30'0"W 71°27'30"W 71°25'0"W 71°22'30"W

44°30'0"N 44°30'0"N 32 td td td 180 td Pt DESCRIPTION OF MAP UNITS Ha Pg 220 Pt Stream or lake

36 Artificial fill— Earth m ate rial of various sorts, use d as road fill. Shown af Pt 110 7 only whe re thick e nough to alte r the top ograp hic m ap contours.

50 td Qls HOLOCEN E DEP OSITS 122 Stream alluvium— Sand , grave l, and silt d e p osite d on the flood p lains of Qf Ha Pg Qf td stre am s. Unit m ay includ e som e we tland are as.

24 Wetland deposits— P e at, m uck, silt, and clay. De p osite d in p oorly d raine d 20 Hw 3 8 Qfb1 are as. 6 6 Qfb1 120 QUATERN ARY DEP OSITS td 3 22 131 Qfb2 Israel deposits — Unclassifie d glacial to p ostglacial sand and Qirvd grave l in the Israe l Rive r valle y. Most of this unit occurs in the ad jace nt Mount Dartm outh q uad rangle to the south (Fowle r and Barke r, 2015). Qfb1 td Stream terraces — Sand and grave l d e p osite d on form e r flood -p lain td Qst Pg surface s along the Israe l Rive r and othe r stre am s. Qfg Fan deposits (undifferentiated) — Alluvial fans form e d along the m id to Qf Pt Qls lowe r re ache s of stre am s that d rain the ste e p m ountain slop e s which occur ove r m uch of the m ap are a. Typ ically com p ose d of ve ry coarse , p oorly- sorte d p e b b le -b ould e r grave l and m inor sand .

Y ounge r fans d e p osite d b y Bunne ll Brook. Qfb2 Qfg 75 40 Old e r fans d e p osite d b y Bunne ll Brook. 8 Ha Qfb1

Garland b rook fan. 8 td Qfg 14 Stag Hollow Brook fan. Qfsh 15 19 Pt

9 9 Landslide areas— Zone of single or m ultip le slop e failure s, includ ing: (1) Qls 25 5 cluste r of se ve ral ve ry ste e p d e b ris avalanche tracks on the south face of the 44°27'30"N 44°27'30"N 20 rid ge b e twe e n Mount Starr King and Mount W aum b e k in Je ffe rson: and (2) 105 80 22 zone of slum p m ove m e nts with arc uate he ad scarp s along the up p e r p art of Bunne ll Brook in Lancaste r and Kilke nny; and (3) a rockslid e or d e b ris avalanche on the southe ast e nd of Te rrace Mountain in Kilke nny. Avalanche 8 d e p osits m ay includ e variab le p rop ortions of re worke d till and colluvium Pt 14 toge the r with b e d rock b locks from local outcrop s. Slum p d e p osits m ay 12 includ e re worke d till, colluvium , stre am grave l, and fine -graine d se d im e nts d e p osite d in ice -d am m e d p ond s. Ad d itional land slid e s are like ly to occur in re m ote m ountainous te rrain of the W hite Mountain N ational Fore st.

3

31 P LEISTOCEN E DEP OSITS 29 Israel deposits — Glacial Lake Israe l d e p osits. Sand and Pli grave l d e p osite d into Lake Israe l, which e xiste d whe n the lowe r Israe l Rive r 21 valle y was d am m e d b y the re ce d ing glacial ice m argin. The up p e r surface s of the se d e p osits we re at le ast p artly te rrace d as the lake le ve l d rop p e d and the p ostglacial Israe l Rive r b e gan to re work and cut d own through the td glacial lake se d im e nts. Sm all are as of sand and grave l of p rob ab le glacial origin, b ut whose Pg d e p ositional e nvironm e nts are unknown.

Ice-contact deposits — Sand and grave l d e p osite d b y glacial m e ltwate r td Pgi stre am s in contact with re m nant m asse s of stagnant ice . Occurs along Big Le d ge Brook in Rand olp h.

20 — Rid ge s of grave l and m inor sand d e p osite d b y m e ltwate r stre am s Pge in sub glacial ice tunne ls. Eske rs occur in the Israe l Rive r valle y in

Qls Je ffe rson, and on the lowe r southe ast slop e of P liny Mountain in Rand olp h.

 21 

   10  End complex — Are a of short m oraine rid ge s and till hum m oc ks

Pemc 1   d e p osite d at the m argin of the Laure nd tid e Ice She e t as it re ce d e d north- 3 1 4 1 2 3 1 6 northwe st from the Israe l Rive r valle y. In this are a, m any rid ge s and 15 1 12 5 3 18 1 2 5 5 4 5 16 5 hum m ocks of stony till are inte rsp e rse d with low are as includ ing p atche s of 13 6 we t ground . Qf 8 12 Till — Loose to ve ry com p act, p oorly sorte d , m assive to we akly stratifie d Pt m ixture of sand , silt, and grave l-size rock d e b ris. De p osite d d ire ctly from 9 Pt glacial ice . May includ e le nse sm of wate rlaid sand and grave l. 40 8 Thin-drift areas — "td " ind icate s are as whe re outcrop s are com m on and /or 60 td surficial se d im e nts are infe rre d to b e ge ne rally le ss than 10 ft thick. Map p e d 7 p artly from air p hotos and LiDAR im age ry, e sp e cially in re m ote are as, 56 36 whe re thin-d rift are as are like ly m ore e xte nsive than shown he re . 20 18 44°25'0"N 44°25'0"N

× Qf × Pt 24 Pge × × × × 24 × × 21 × Pge × EXPLANATION OF MAP SYMBOLS × × × × × × × × Contact Bound ary b e twe e n m ap units, d ashe d whe re infe rre d . × 17 td × td × Water well × × Pgi Lab e l ind ic ate s d e p th to b e d roc k in fe e t. × Qf 7 5 Pt Bedrock outcrop Ind ivid ual b e d rock outcrop s, com m on in thin d rift. × × Pge × 77 × Hw × × × Glacial striation Arrow shows glacial ice -flow d ire c tion infe rre d

Qst × 16 26  ×  from striations on b e d roc k. Dot m ark p oint of × 14 locality

× 4.5 td   ob se rvation. N um b e r is azim uth (in d e gre e s) of flow × × 39 5 (multiple present)

1  d ire ction. Multip le arrows ind icate site s with two or

20 30  1 45 11 m ore striation se ts d ue to changing flow d ire c tions. 6

12 Sp illway for Baile ys (Ba) Stage of glacial Lake Qst 12 9 Spillway 15 15 Ba Israe l - "339" is the ap p roxim ate e le vation (in Pemc 120 6 m e te rs) of the sp illway through which the lake 7 120 wate r e scap e d we stward through the Che rry P ond 17 82 are a and into the up p e r Johns Rive r (Lancaste r 8 68 q uad rangle ). 105 Pg Infe rre d shore line of glacial Lake Israe l d uring Pt Shoreline 26 Qf 210 Qfsh Baile ys Stage - Locate d ap p roxim ate ly, b ase d on the 30 339 m sp illway e le vation.

26 , Glacially Sym b ol shows axis of sm ooth till rid ge which has Ha streamlined till b e e n e longate d and stre am line d b y glacial ice flow.

af ridge , Ha Pt Line m arks axis of till rid ge d e p osite d at the m argin 30 Moraine ridge Qst of the last glacial ic e she e t d uring a p ause in its re ce ssion. Qst Ha 35 Channe l e rod e d b y glac ial m e ltwate r stre am . Arrow 162 Meltwater channel Pli shows infe rre d d ire ction of form e r stre am flow. 53 af 48 Pli 217 186 98 182 Hw 192 48 15 × × × × Che vron sym b ols show the axis of the e ske r and Qfsh 30 168 28 p re sum e d m e ltwate r flow d ire c tion whe n it was Ba Hw 36 Qirvd d e p osite d . Qfsh 44°22'30"N 44°22'30"N Ha

71°30'0"W 71°27'30"W 71°25'0"W 71°22'30"W

Topographic basemap from the USGS 1998 Jefferson 7.5' quadrangle Projection: North American Datum 1983 New Hampshire State Plane Feet. Scale 1:24,000 1000 meter grid in UTM zone 19 North, Contour Interval 6 m Surficial Geology of the Hillshade produced from high resolution (1 meter and 10 meter) LiDAR data 0 1,450 2,900 5,800 Jefferson 7.5' Quadrangle, New Hampshire Feet 0 0.5 1 2

Miles Surficial Ge ology b y W ood row B. Thom p son Digital Com p ilation b y Sarah W . Bake r and Gre gory A. Barke r 0 1 2 4 N e w Ham p shire State Ge ologist: Fre d e rick H. Chorm ann Kilometers

GROVETON STARK WEST MILAN Surficial Ge ologic Map Op e n-File Se rie s GEO-037-024000-SMOF

This geologic map was funded in part by the USGS National Cooperative Geologic Mapping Program under StateMap award number G15AC00504 MOUNT LANCASTER E CRESCENT New Hampshire Geological Survey NH Department of Environmental Services 29 Hazen Drive, P.O. Box 95

MOUNT MOUNT Concord, NH 03302-0095 BETHLEHEM E DARTMOUTH WASHINGTON NHGS Open-File Disclaimer: This map and the accompanying legend(s) are understood to be open-file products. They are draft versions of an unpublished report and represent mapping Phone: 603-271-1976 progress at the time of completion. Newer information may exist. If you have questions, please E-mail: [email protected] contact the New Hampshire Geological Survey (NHGS) at: [email protected] or (603) 271-1976 1

SURFICIAL GEOLOGY OF THE JEFFERSON 7.5-MINUTE QUADRANGLE, COOS COUNTY, NEW HAMPSHIRE By Woodrow B. Thompson 171 Lord Road Wayne, ME 04284

For the New Hampshire Geological Survey 2016

INTRODUCTION

This report describes the surficial geology and Quaternary history of the Jefferson 7.5-minute quadrangle, located in the northern part of New Hampshire’s White Mountains. Surficial earth materials include unconsolidated sediments (sand, gravel, etc.) of glacial and nonglacial origin. Most of these deposits formed during and after the latest episode of glaciation, within the last 25,000 years. Surficial sediments cover the bedrock over hillsides and valley bottoms in the quadrangle, and are subject to various land-use considerations. These include sand and gravel extraction, development and protection of ground-water supplies, siting of waste disposal facilities, selection of building sites, and agriculture. The field work and map compilation for this study were carried out by the author in support of the STATEMAP cooperative between the New Hampshire Geological Survey and the U. S. Geological Survey (USGS). The geologic map accompanying this report shows the distribution of sedimentary units, and indicates their age, composition, and known or inferred origin. It also includes information on the geologic history of the quadrangle, such as features indicating the flow direction of glacial ice. This map provides the basis for the discussion of glacial and postglacial history presented here. Geographic setting. The map area extends in latitude from 44o22'30" to 44o30'00" N, and in longitude from 71o22'30" to 71o30'00" W. It encompasses much of Jefferson, and parts of the towns of Lancaster, Kilkenny, Berlin, and Randolph. A large irregular area in the central to northern portions of the quadrangle lies within the White Mountain National Forest. Residential development is concentrated along U. S. Route 2 and numerous other roads in the southern and western parts of the map area, almost entirely in Jefferson and Lancaster. Otherwise, much of the quadrangle is forested wilderness with few roads and trails. The Jefferson area has been popular with vacationers since the 1800s, when it was opened to tourism by the expanding railroad network and hotel construction. The area was further publicized by the nationally known minister and author Thomas Starr King (after whom one of the local mountains was named). He vacationed there and published a book titled “The White Hills: Their Legends, Landscape, and Poetry”. 2

The quadrangle lies mostly in the River drainage basin. The principal stream in the map area is the Israel River, which flows northwestward and meets the in Lancaster. It has many tributary brooks that drain the southern and western slopes of the mountains in the National Forest. There are virtually no lakes or natural ponds in the quadrangle. Except for the Israel Valley, the topography of the area is largely hilly to mountainous. Elevations range from about 1020 ft in the northwest corner of the map area to 4006 ft on the summit of Mount Waumbek in Kilkenny. Bedrock geology. Quaternary sediments extensively cover the bedrock at lower elevations in the Jefferson quadrangle, but ledge outcrops are common on the hills and mountain tops, and occur locally in stream beds and other places. The bedrock includes various igneous and metamorphic rocks of Ordovician to Jurassic age. The bedrock geology of the Jefferson quadrangle was mapped by Billings et al. (1979) as part of their Mt. Washington 15-minute quadrangle report, and subsequently reinterpreted and compiled at a scale of 1:250,000 on the latest bedrock geologic map of New Hampshire (Lyons et al., 1997). The map by Lyons et al. (1997) shows that most of the Jefferson quadrangle is underlain by a large oval body of rock belonging to the Oliverian Plutonic Suite of Ordovician age. This gneissic rock unit is cut by concentric shells of Jurassic igneous rocks of generally intermediate to granitic/syenitic composition. Parts of the latter units were intruded in turn by the Jurassic Conway . Collectively, these intrusions are known as the Pliny Range Caldera Complex. They are the subject of recent detailed mapping for the New Hampshire Geological Survey’s STATEMAP program (Baker et al., 2016; Cargill et al., 2016). The new work has extended the age of the complex back to the Silurian period.

PREVIOUS WORK No large-scale or detailed surficial geologic mapping has been conducted previously in the Jefferson quadrangle. Detailed surficial mapping of adjacent areas has been carried out by Hildreth (2013) in the Mount Crescent quadrangle to the east, and by Fowler and Barker (2015) in the Mount Dartmouth quadrangle to the south. The 2003 soil survey of Coos County by the U. S. Department of Agriculture’s Natural Resources Conservation Service provided useful materials information for sites that the present author did not visit in the field. Additional information on glacial and postglacial geomorphology was derived from air photo interpretation and from LiDAR imagery that is presently available only in the area of the White Mountain National Forest.

DESCRIPTION OF GEOLOGIC MAP UNITS The surficial deposits represented on the geologic map have been classified on the basis of their age and origin. Map units are designated by letter symbols, such as "Pt". The first letter indicates the age of the unit: "P", (); "H", Holocene (postglacial, i.e. formed during the last 12,000 years); "Q", Quaternary (encompasses both the Pleistocene and Holocene epochs) 3

The Quaternary age is assigned to units which overlap the Pleistocene-Holocene boundary, or whose ages are uncertain. The other letters in the map symbol indicate the origin and/or assigned name of the unit, e.g. "t" for till and "gi" for glacial ice-contact deposits. Surficial map units in the Jefferson quadrangle are described below, starting with the older deposits that formed in contact with glacial ice. Till (map unit Pt) Till is a glacially deposited sediment consisting of a more-or-less random mixture of sand, silt, and gravel-size rock debris. It may also include numerous boulders. Till is the most widespread surficial deposit in the quadrangle. It blankets the hills and sides of mountains, although parts of it have been disturbed by mass movements and surface water runoff on the steeper slopes. Test borings in show that till commonly extends beneath the younger waterlaid sediments in valleys. Most exposures of till in the Jefferson quadrangle are shallow cuts (3-6 ft) along town roads and logging roads. In a few places, small borrow pits and excavations next to woods roads have revealed up to 20 ft of till (Fig. 2). The thickness may be considerably greater beneath some of the valley sides, where the smooth topography suggests a thick build-up of till. Several well logs in the Jefferson Highlands area record a great thickness of overburden (up to 217 ft), most or all of which probably is till. Till is thin or absent on the tops of most hills and mountains in the quadrangle, where bedrock is likely to be exposed. The geologic map indicates areas where bedrock outcrops are common and/or the till thickness is inferred to be less than 10 ft. Till is, by definition, a poorly sorted sediment (diamicton) in which there is a wide range of rock and mineral particle sizes. However, the texture and structure of individual till deposits vary depending on their source and how they were formed. Till in the map area may include a small percentage of clay, but it has a dominantly sandy or silty-sandy matrix as a consequence of having been derived from coarse-grained bedrock. Till has little or no obvious stratification in some places. Elsewhere it is crudely stratified, with discontinuous lenses and laminae of silt, sand, and gravel resulting from sorting by meltwater during deposition. Stones are abundant in this map unit, and boulders scattered across the ground surface often indicate the presence of till. Till stones in the quadrangle chiefly consist of igneous and metamorphic rocks that were glacially eroded from local bedrock sources. Most till stones are more-or-less angular, and a small percentage have smooth, flat, striated surfaces due to glacial abrasion. These faceted surfaces are best developed on dense, fine-grained rocks such as basalt or fine-grained metamorphic rocks. In small exposures, it is often difficult to identify varieties of till and how they formed, but most of the till in the quadrangle is likely to be either lodgement till or till. Lodgement till was deposited under great pressure beneath the . It may be very compact and difficult to excavate, with a platy structure (fissility) in the upper, weathered zone. Large areas of thick till and smooth topography on hillsides in the quadrangle are likely to be lodgement deposits. Ablation till was formed during the melting of the ice, in unstable glacial environments where slumping and meltwater action were common. This type of till tends to be loose-textured and 4 stony, with numerous lenses of washed sediment. In places a thin veneer of stony ablation till may overlie finer-grained lodgement till. Field studies in New England (e.g. Koteff and Pessl, 1985; Weddle et al., 1989), suggests that till deposits of two glaciations may present in the region. The "upper till" is the product of the most recent, late Wisconsinan glaciation () which covered central New Hampshire between about 25,000 and 15,000 years ago. Exposures of upper till can be seen in many shallow pits, road cuts, and temporary excavations. It is not weathered (except in the near- surface zone of modern soil formation) and commonly is light olive-gray to olive in color. The "lower till" consists of compact, silty-sandy lodgement deposits. This older till is most common in southern New England, where it is distinguished by its thick weathering profile that may extend to a depth of 10 ft or more. Within this weathered zone, the till is oxidized and has an olive-gray to dark olive-gray or dark grayish-brown color. Dark-brown iron/manganese oxide staining coats the surfaces of stones and joints. This till is believed to have been deposited during an earlier glaciation in time, prior to 130,000 years ago (Weddle et al., 1989). Exposures of the lower till are relatively uncommon in northern New England, and none have been found in the Jefferson quadrangle. This may be due to the lack of deep excavations, but it is also possible that a greater degree of erosion by the last glacial ice sheet either has removed much of the lower till in the region, or at least has eroded away the diagnostic oxidation zone. The two tills have been observed together at just a few localities, especially in the Nash Stream valley in northern New Hampshire (Koteff and Pessl, 1985). The Nash Stream site is in Stratford, not far to the north of the Jefferson. End moraine complex (unit Pemc) A sizable part of the Israel Valley, in the vicinity of Route 115A, is a forested area with a complex group of many small, stony till ridges and mounds, separately by low areas of till and wet ground. The ridges and mounds are interpreted as that were deposited at the margin of the Laurentide Ice Sheet during brief pauses in its overall retreat. Most of the distinct moraine ridges trend east-west, suggesting that the ice margin had that same orientation and retreated northward from this part of the valley. These ridges are up to ~20 ft high and 100-300 ft long, and boulders commonly occur on their surfaces (Fig. 3). A small pit in one of the moraines showed a nice longitudinal cross section that exposed ~15 ft of light olive- gray, non-stratified, sandy and very stony, loose to compact till (Fig. 4). Most of the stones are subangular to angular, and a few are striated. This moraine complex is on the northern fringe of a major belt of end moraines that extends discontinuously from Littleton across the northern White Mountains to Berlin, New Hampshire. The moraine clusters in the Littleton-Bethlehem area have been studied by many geologists since the mid 1800s (Thompson, 1999a), while Thompson et al. (1999; 2009) traced the moraine belt eastward almost to the border. A 1:100,000-scale map of the moraine belt and associated deglaciation features has been compiled by Thompson and Svendsen (2015) and continues to be updated. Collectively, the moraines were deposited by glacial readvance and oscillatory retreat during the Litteton-Bethelehem Readvance. This event resulted from climate cooling in the North Atlantic region ca. 14,000 years ago (e.g. Ridge et al., 2012) 5

Esker deposits (unit Pge) Eskers are ridges of gravel and sand that accumulated in ice-walled tunnels at the base of a . They were deposited by high-energy subglacial streams driven by the pressure of the surrounding ice sheet. These streams deposited sediments in the ice tunnels, and after the glacier melted, the tunnel paths were marked by gravelly ridges that remain today. Eskers were mapped in two areas of the Jefferson quadrangle. The most prominent example trends southeast along the lower north side of the Israel River valley. It extends from Route 116 to Route 115A. Gravel pits have been worked in this esker intermittently from the 1930s to the present day. The gravel is up to boulder size, and some of it is very well rounded (Fig. 6). Other eskers were mapped on the hillside between Pliny Mountain and Big Ledge Brook, near the eastern border of the quadrangle (Fig. 5). LiDAR imagery shows two northeast-trending ridges in this area. At first they were suspected to be moraines and possibly deposited by the that formed a large moraine on the west side of Pond of Safety (Randolph) in the neighboring Mt. Crescent quadrangle (Thompson and Svendsen, 2015). However, these ridges were found to be eskers composed of pebble-boulder gravel. They are inferred to have resulted from northeastward meltwater flow related to the same ice tongue that built the Pond of Safety moraine a short distance to the east. Ice-contact deposits (unit Pgi) An area of sand and gravel next to Big Ledge Brook in Randolph is interpreted as having been laid down in contact with stagnant glacial ice. Thus it was mapped as an ice-contact deposit, based on its partly elevated topography relative to the valley floor, as well as scattered boulders and poorly rounded gravel clasts seen in an old pit face.

Waterlaid glacial deposits of uncertain origin (Unit Pg) A few areas of sand and gravel – located in hilly terrain in the northern and SE parts of the quadrangle – could not be classified because of the lack of diagnostic exposures. These deposits are thought to have been deposited by meltwater issuing from glacial ice. They may have been emplaced in glacial streams and/or in meltwater ponds between the ice margin and adjacent hillsides.

Glacial Lake Israel deposits (unit Pli) This poorly exposed unit consists of mixed sand and minor gravel deposited into Lake Israel, which existed when the lower Israel River valley was dammed by the glacial ice margin as it receded toward Lancaster. The upper surfaces of these deposits are generally somewhat horizontal, suggesting they are either the original tops of deltas built into the lake, or that they were terraced when the lake drained and the postglacial Israel River began to rework and cut down through the glacial lake sediments.

The 338 m elevation of the Pli deposit near the junction of Routes 115 and 115A matches the spillway elevation (in the SW corner of the map) for the Baileys Stage of glacial Lake Israel. Thus, this deposit is either an original delta built to that lake level, or it may be an earlier and 6 higher lake deposit that the early Israel River trimmed down to the level of the Baileys Stage when the lake dropped to this elevation.

The other Pli deposit (on the north side of the valley) reaches elevations of 348 to about 354 m. It presumably formed in the higher and earlier Bowman Stage of Lake Israel and later was terraced by the Israel River.

Landslide areas (unit Pls) This map unit designates zones of single or multiple slope failures, including: (1) a cluster of several very steep debris avalanche tracks on the south face of the ridge between Mount Starr King and Mount Waumbeck in Jefferson; and (2) zone of slump movements with arcuate headscarps along the upper part of Bunnell Brook in Lancaster and Kilkenny; and (3) a rockslide or debris avalanche on the southeast end of Terrace Mountain in Kilkenny. The Bunnell Brook slumps probably were triggered by ground-water conditions related to glaciolustrine sediments. Ponding of glacial meltwater probably occurred in this and other W or NW-sloping valleys at the last ice sheet retreated, resulting in local deposition of lacustrine clay, silt, and sand. These conditions were inferred from a small (unmapped) slump scarp next to the trail along Bunnell Brook showing stony colluvium and poorly sorted gravel overlying stratified silt-sand from which ground water was seeping. Mudflows resulting from larger slumps in the past may have deposited the unusual clay-silt observed on the high-level Bunnell Brook fan (Qfb1) described below.

Alluvial fan deposits (units Qfsh, Qfg, Qfb1-2, Qf) Alluvial fans often form in mountainous areas where steep upland streams discharge into broader valleys with gentler slopes. The decrease in stream gradient toward the mouths of these streams causes at least the coarsest part of their sediment lodes to be deposited. Many fans in New Hampshire’s mountainous areas are believed to have formed in large part soon after deglaciation, when barren, freshly-exposed mountain slopes would have been vulnerable to rapid erosion during torrential rain storms. Rare deluges probably have contributed to fan growth in postglacial time, so these deposits are assigned a general Quaternary age. The most prominent fans in the Jefferson quadrangle are the Stag Hollow Brook fan (unit Qfsh), Garland Brook fan (Qfg), and the Bunnell Brook fan (Qfb1-2). These three brooks drain most of the high mountainous terrain in the eastern half of the map area. The Bunnell Brook fan is interpreted as a two-stage deposit, in which an earlier high-level fan surface (Qfb1) was incised and the lower Qfb2 fan was formed (Fig. 7). Exposures of unit Qfb1 show a variety of materials including diamicton, clay-silt, and sand to gravelly sand. The thickness of this unit is unknown; it may be just a shallow deposit over till. Unit Qfb2 consists of very coarse gravel with many boulders to 3 ft and larger in diameter. The lower part of the latter fan adjoins the Garland Brook fan and is probably about the same age. The Garland Brook and Stag Hollow Brook fans are composed of very coarse pebble-boulder gravel in their mid to upper parts and transition to finer gravel and sand in the downstream direction. The Garland Brook fan extends far down its valley and is much more gently sloping in 7 its lower reach. A pit in the Stag Hollow Brook fan (Fig. 8) shows a total exposed thickness of about 40 ft of gravel and sand. Stream terraces (unit Qst) Stream terraces (Qst) in the Jefferson quadrangle are remnants of past flood plains that were abandoned as streams eroded down to their modern levels. The map unit occurs mainly in the Israel River valley (Fig. 9). These flat-topped terraces may be just erosional in some places, where glacial sediments were partly removed by postglacial stream action, or they may contain sand and gravel reworked from the older sediments and deposited on the erosion surface. No pit exposures were found in the terraces, but the surface materials are most likely sand and gravel in varying proportions. Although generally higher than today’s flood plain, some of the terraces along the Israel River may still be inundated by major floods. Israel River valley deposits (unit Qirvd) Map unit Qirvd occurs in a very small area at the south edge of the Jefferson quadrangle. It is thought to be equivalent to unit Qst, but has been matched with unit Qirvd on the adjacent Mount Dartmouth surficial quadrangle map by Fowler and Barker (2015). Wetland deposits (unit Hw) Unit Hw consists of fine-grained and organic-rich sediments deposited in low, flat, poorly drained areas. This unit occurs in a few small upland areas, and in some poorly drained environments associated with flood plains. Only the major wetlands have been shown here, based mostly on air photo interpretation. Thin unmapped wetland areas may be expected in other places as well. The surficial geology map should not be interpreted a definitive wetlands map for purposes of land-use planning and regulation. Stream alluvium (unit Ha) Unit Ha consists of alluvial sand, gravel, silt, and organic material deposited by late-glacial to modern streams. Sediment textures vary widely depending on the local depositional environment. In general there is a high percentage of coarse gravel along streams in the mountainous terrain of the Jefferson quadrangle, while sand, fine gravel, and silt are common along lower-gradient streams such as the Israel River (Fig. 10). Artificial fill (unit af) Fill has been mapped in only two places (along U. S. Route 2) where it is present in large enough amounts to be reflected in the contour pattern of the topographic map.

GLACIAL AND POSTGLACIAL GEOLOGIC HISTORY Glaciation 8

The following reconstruction of the Quaternary history of the Jefferson quadrangle is based on the author's interpretations of surficial earth materials described in this report, as well as topographic features in the study area. The most recent (late Wisconsinan) glaciation began about 25,000 years ago, when the Laurentide Ice Sheet in Canada spread southward across New England (Stone and Borns, 1986). It produced the stony till deposits that blanket large areas of the quadrangle. Rocks torn from the hills were scattered in the direction of glacial transport. Abrasion by rock debris dragged at the base of the glacier smoothed the bedrock and left scratches (striations) parallel to the direction of ice flow (Fig. 1). Deep and broad striations are called “glacial grooves”. In many places striations are not evident because they are either concealed beneath surficial sediments or have been destroyed by weathering at the ground surface. The geologic map shows sites in the quadrangle where striation trends have been recorded. Most data came from ledges along road sides and hiking trails. Some of these occurrences are limited to very small remnants of glacially polished surfaces on otherwise weathered ledges, and the striations in such cases may be visible only after rubbing a pencil across the rock surface. Glacial striations and grooves usually can be seen more easily on wet surfaces. Striation data from the quadrangle indicate glacial flow directions between southeast and east south-southeast. This flow probably occurred during the maximum phase of late Wisconsinan glaciation. Glacially streamlined till ridges with a similar trend occur in a few places such as the unnamed hill near the southwest corner of the quadrangle. Deglaciation The time of glacial retreat from the quadrangle can be approximated from radiocarbon dating and correlation of sequences of annual clay layers (varves) deposited in glacial Lake Hitchcock in the Connecticut River valley (Ridge et al., 2012). Eastward extrapolation of the Lake Hitchcock varve chronology suggests that the glacier receded from the study area nearly 14,000 years ago. Melting of the Laurentide Ice Sheet would have simultaneously produced thinning of the ice sheet and recession of its margin. The configuration of the ice margin in the rugged terrain of the Jefferson quadrangle probably was irregular, with tongues of active ice persisting in west to north-facing valleys when nearby mountain peaks had already emerged from the ice sheet. Small end moraines are present on the north side of the Israel valley. These moraines, and the orientations of meltwater channels carved on hillsides by glacial streams, support a northward to northwestward recession of the ice margin. A great quantity of rock debris was released from the Laurentide Ice Sheet as it melted. Some of this material washed out of the ice, but much of it was simply dumped on the land surface with little or no reworking by meltwater, forming a widespread blanket of stony glacial till across the quadrangle. 9

Meltwater streams from the receding ice sheet deposited esker gravel in tunnels beneath the glacier. Sand and gravel washed into Lake Israel and probably into a few ephemeral ice- dammed ponds between the glacier margin and adjacent mountain slopes. Postglacial events During and after deglaciation of the Jefferson quadrangle, nonglacial streams began to establish their modern drainage patterns. As soon as the ice retreated, the freshly deposited glacial sediments on mountain sides were very susceptible to erosion until a vegetation cover was established. The numerous gravelly alluvial fans probably formed at this time. Early postglacial stream alluvium forms the river terraces (unit Qst) that stand higher than the present-day flood plain along the Israel River and lower part of Stag Hollow Brook. Deposits of recent flood-plain alluvium (unit Ha) continue to accumulate along these and other streams, and organic-rich sediments (unit Hw) are being deposited in wetlands. Most of the alluvial sand and gravel transport along streams in the area presumably occurs when water levels are high during spring runoff and storm events. ECONOMIC GEOLOGY Sand and gravel resources are found mainly in valley areas of New Hampshire, where they have been concentrated by glacial and postglacial stream deposition. In the Jefferson quadrangle, extraction of sand and gravel deposits has occurred in many small pits along the Israel River valley. Most of this activity has been in stream terraces (unit Qst), glacial Lake Israel sediments (unit Pli), and the esker ridge (unit Pge) located between Routes 116 and 115A. There has also been some gravel extraction from upland alluvial fan deposits (unit Qf). Much of the sandy till in the quadrangle has a silty-sandy matrix that compacts well in applications where fill is needed. ACKNOWLEDGEMENTS The author is grateful to the USDA’s Natural Resources Conservation Service (NRCS) office in Lancaster, N.H. for use of their air photos, and to the New Hampshire Geological Survey for cartographic support, LiDAR imagery, and parent materials maps for soil units mapped by the NRCS. Several people assisted with field logistics. Dennis Field (Lancaster) and Doug Robertson (Warren, NH) provided good company during hiking trips and transportation on several woods roads requiring a high-clearance vehicle. Unpublished test-boring logs were supplied by the NH Department of Transportation, and Richard Boisvert (NH Division of Historical Resources) and Chris Dorion provided information on the stratigraphy of archaeological site excavations in Jefferson. The Jefferson town office and numerous local residents were very helpful in providing land ownership information and granting access to their properties. In particular, I thank Paul Crane, George Cook IV, Neil Gross, Mitch Ingerson, Craig Kluckie, Mr. & Mrs. Charles Larcomb, and Bob Lottero for much helpful information about the history and landscape of the Israel River valley and Lancaster areas. REFERENCES 10

Baker, S. W., Cargill, J., Eusden Jr., J. D., Bradley, D. C., and Boisvert, R. A., 2016, Bedrock geology of the Jefferson 7.5’ quadrangle, New Hampshire: Geological Society of America, Abstracts with programs, v. 48, no. 2, paper 27-1.

Billings, M. P., Fowler-Billings, K., Chapman, C. A., Chapman, R. W., and Goldthwait, R. P., 1979, The geology of the Mt. Washington Quadrangle, New Hampshire: Concord, New Hampshire Department of Resources and Economic Development, 44 p. and 1 plate.

Boisvert, R. A., 1999, Paleoindian occupation of the White Mountains, New Hampshire, in Thompson,W. B., Fowler, B. K., and Davis, P. T., eds., Late Quaternary History of the White Mountains, New Hampshire and Adjacent Southeastern Québec: Géographie physique et Quaternaire, v. 53, no. 1, p. 159-174.

Cargill, J., Baker, S. W., O’Sullivan, P. B., Eusden Jr., J. D., and Bradley, D. C., 2016, Structure and geochronology of the Jurassic Pliny Range Caldera Complex: 7.5’ Jefferson quadrangle, northern New Hampshire: Geological Society of America, Abstracts with programs, v. 48, no. 2, paper 34-7.

Eusden, J. D., Thompson, W. B., Fowler, B. K., Davis, P. T., Bothner, W. A., Boisvert, R. A., and Creasy, J. W., 2013, The geology of New Hampshire’s White Mountains: The Durand Press, Lyme, NH, 175 p.

Fowler, B. K., and Barker, G. A., 2015, Surficial geologic map of the Mount Dartmouth 7.5- minute quadrangle, New Hampshire: Concord, New Hampshire Geological Survey, Map Geo- 046-024000-SMOF.

Hildreth, C. R., 2009, Surficial geologic map of the Mount Crescent 7.5-minute quadrangle, New Hampshire: Concord, New Hampshire Geological Survey, Map Geo-044-024000-SMOF.

Koteff, C., and Pessl, F., Jr., 1985, Till stratigraphy in New Hampshire: Correlations with adjacent New England and , in Borns, H. W., Jr., LaSalle, P., and Thompson, W. B., eds., Late Pleistocene history of northeastern New England and adjacent Quebec: Geological Society of America, Special Paper 197, p. 1- 12. Lougee, R. J., 1939, Geology of the Connecticut watershed, in Warfel, H. E. (Ed.), Biological Survey of the Connecticut Watershed: Concord, New Hampshire Fish and Game Department, Report 4, p. 131–149.

Lyons, J. B., Bothner, W. A., Moench, R. H., and Thompson, J. B., Jr., 1997, Bedrock geologic map of New Hampshire: U. S. Geological Survey, 1:250,000-scale map. Olimpio, J. R., and Mullaney, J. R., 1997, Geohydrology and water quality of stratified-drift aquifers in the upper Connecticut and basins, northern New Hampshire: Pembroke, NH, U. S. Geological Survey, Water-Resources Investigations Report 96-4318, 161 p. and plates. 11

Ridge, J. C., Balco, G., Bayless, R. L., Beck, C. C., Carter, L. B., Dean, J. L., Voytek, E. B., and Wei, J. H., 2012, The new North American Varve Chronology: A precise record of southeastern Laurentide Ice Sheet deglaciation and climate, 18.2-12.5 kyr BP, and correlations with Greenland records: American Journal of Science, v. 312, p. 685–722.

U. S. Natural Resources Conservation Service and the Coos County Conservation District (Lancaster Field Office), 2003, Soil Survey of Coos County Area, New Hampshire: CD data release.

Stone, B. D., and Borns, H. W., Jr., 1986, Pleistocene glacial and stratigraphy of New England, Long Island, and adjacent Georges Bank and the Gulf of Maine, in Sibrava, V., Bowen, D. Q., and Richmond, G. M., eds., Quaternary glaciations in the Northern Hemisphere -- IGCP Project 24: Oxford, England, Pergamon Press, p. 39-53. Thompson, W.B., 1999a, History of research on glaciation in the White Mountains, New Hampshire (U.S.A.), in Thompson,W. B., Fowler, B. K., and Davis, P. T., eds., Late Quaternary History of the White Mountains, New Hampshire and Adjacent Southeastern Québec. Géographie physique et Quaternaire, v. 53, no. 1, p. 7-24. Thompson, W. B., and Svendsen, K. M., 2013, Glacial lakes and related deglaciation features in the northern White Mountains, New Hampshire (abs.): Geological Society of America, Abstracts with programs, v. 45, no. 1, p. 105. Thompson, W. B., and Svendsen, K. M., 2015, Deglaciation features of the northern White Mountains, NH: Concord, New Hampshire Geological Survey, Open-File Map (1:100,000 scale). Thompson, W. B., Fowler, B. K., and Dorion, C. C., 1999, Deglaciation of the northwestern White Mountains, New Hampshire, in Thompson, W. B., Fowler, B. K., and Davis, P. T., eds., Late Quaternary history of the White Mountains, New Hampshire and Adjacent Southeastern Québec: Géographie physique et Quaternaire, v. 53, no. 1, p. 59-78. Thompson, W. B., Boisvert, R. A., Dorion, C. C., Kirby, G. A., and Pollock, S. G., 2009, Glacial geology, climate history, and late-glacial archaeology of the northern White Mountains, New Hampshire (Part 2), Trip C3 in Westerman, D. S., and Lathrop, A. S., eds., Guidebook for field trips in the Northeast Kingdom of and Adjacent Regions: Lyndon State College, Lyndonville, VT, guidebook for 101st annual New England Intercollegiate Geological Conference, p. 225-242.

Thompson, W., Ridge, J., and Springston, G., 2011, Glacial geology of the upper Connecticut River Valley, Littleton-Lancaster, NH, and Barnet-Guildhall, VT: Guidebook for joint summer field trip of the Geological Society of New Hampshire and Vermont Geological Society, 23 p.

Weddle, T. K., Stone, B. D., Thompson, W. B., Retelle, M. J., Caldwell, D. W., and Clinch, J. M., 1989, Illinoian and late Wisconsinan tills in eastern New England: A transect from northeastern to west-central Maine, in Berry, A. W., Jr., ed., Guidebook for field trips in southern and west- central Maine: Farmington, Maine, University of Maine at 12

Farmington, New England Intercollegiate Geological Conference, guidebook for 81st annual meeting, Trip A-2, p. 25-85.

13

GLOSSARY OF TERMS (updated and expanded from glossary originally compiled by John Gosse and Woodrow Thompson for the Maine Geological Survey mapping program) Ablation till: till formed by release of sedimentary debris from melting glacial ice, accompanied by variable amounts of slumping and meltwater action. May be loose and stony, and contains lenses of washed sand and gravel. Alluvial: refers to sediments or processes resulting from the action of running water, such as the alluvium found on river flood plains. Alluvial fan: an accumulation of sediment typically deposited where a relatively steep upland stream enters a valley and the sudden decrease in stream gradient causes much of its load to be deposited. Often develops a fan-shaped outline as it spreads into the valley. Usually has a noticeable (gentle to moderately steep) surface slope and coarse gravelly sediments. Clast: pebble-, cobble-, or boulder-size fragment of rock or other material in a finer-grained matrix. Often refers to stones in glacial till or gravel. Clast-supported: refers to sediment that consists mostly or entirely of clasts, generally with more than 40% clasts. Usually the clasts are in contact with each other. For example, a well- sorted cobble gravel. Colluvium: sedimentary debris on the lower slopes of hills and mountains. Results from slow downslope movement due to gravity, freeze-thaw action, etc., acting upon preexisting surficial sediments (derived from till in many cases, from which it may be hard to distinguish). Delta: a body of sand and gravel deposited where a stream enters a lake or ocean and drops its sediment load. Glacially deposited deltas in New England usually consist of two parts: (1) coarse, horizontal, often gravelly topset beds deposited in stream channels on the flat delta top, and (2) underlying, finer-grained, inclined foreset beds deposited on the advancing delta front Deposit: general term for any accumulation of sediment, rocks, or other earth materials. Diamicton: any poorly-sorted sediment, containing a wide range of particle sizes, e.g. glacial till. : an elongate oval-shaped hill, often composed of glacial sediments, that has been shaped by the flow of glacial ice, such that its long axis is parallel to the direction of ice flow. End moraine: a ridge of sediment deposited at the margin of a glacier. Usually consists of till and/or sand and gravel in various proportions. Often simply called a “moraine”. Englacial: occurring or formed within glacial ice. Eolian: formed by wind action, such as a sand dune. Esker: a ridge of sand and gravel deposited at least partly by meltwater flowing in a tunnel within or beneath glacial ice. Many ridges mapped as eskers include variable amounts of sediment deposited in narrow open channels or at the mouths of ice tunnels. 14

Fluvial: Formed by running water, for example by meltwater streams discharging from a glacier. Glaciolacustrine / glacial-lacustrine: refers to sediments or processes involving a lake which received meltwater from glacial ice. Glaciomarine / glacial-marine: refers to sediments and processes related to environments where marine water and glacial ice were in contact. Head of outwash: same as outwash head. Holocene: term for the time period from 12,000 years ago to the present. It is often used synonymously with "postglacial" because most of New England has been free of glacial ice since that time. Ice age: see Pleistocene. Ice-contact: refers to any sedimentary deposit or other feature that formed adjacent to glacial ice. Many such deposits show irregular topography due to melting of the ice against which they were laid down, and resulting collapse. : a depression on the ground surface, ranging in outline from circular to very irregular, left by the melting of a mass of glacial ice that had been surrounded by glacial sediments. Many kettles now contain ponds or wetlands. Kettle hole: same as kettle. Lacustrine: pertaining to a lake. Late-glacial: refers to the time when the most recent glacial ice sheet was receding from New England, approximately 20,000-12,000 years ago. Laurentide Ice Sheet: the most recent continental ice sheet that covered New England, in Late Wisconsinan time. Late Wisconsinan: the most recent part of Pleistocene time, during which the latest continental ice sheet covered New England (approx. 25,000-12,000 years ago). Lodgement till: very dense variety of till, deposited beneath flowing glacial ice. May be known locally as "hardpan." Matrix: the fine-grained material, generally silt and sand, which comprises the bulk of many sediments and may contain clasts. Matrix-supported: refers to any sediment that consists mostly or entirely of a fine-grained component such as silt or sand. Generally contains less than 20-30% clasts, which are not in contact with one another. For example, a fine sand with scattered pebbles. Moraine: General term for glacially deposited sediment, but often used as short form of “end moraine”. 15

Outwash: sediment derived from melting glacial ice, and deposited by meltwater streams in front of a glacier. Outwash head: the end of an outwash deposit that was closest to the glacier margin from which it originated. Ice-contact outwash heads typically show steep slopes, kettles and hummocks, and/or boulders dumped off the ice. These features help define former positions of a retreating glacier margin, especially where end moraines are absent. Pleistocene: term for the time period between 2.6 million years ago and 12,000 years ago, during which there were several glaciations. Also called the "Ice Age." Proglacial: occurring or formed in front of a glacier. Quaternary: term for the era between 2.6 million years ago and the present. Includes both the Pleistocene and Holocene. Sorting: the degree to which the rock or mineral particles in a sediment are all the same or similar in size. For example, many glacial tills contain a mixture of rock debris ranging from clay-size to boulders, and thus are very poorly sorted. Striation: a narrow scratch on bedrock or a stone, produced by the abrasive action of debris- laden glacial ice. Plural form sometimes given as “striae”. Subaqueous fan: a somewhat fan-shaped deposit of sand and gravel that was formed by meltwater streams entering a lake or ocean at the margin of a glacier. Similar to a delta, but was not built up to the water surface. Subglacial: occurring or formed beneath a glacier. Till: a heterogeneous, usually non-stratified sediment deposited directly from glacial ice. Particle size may range from clay through silt, sand, and gravel to large boulders. Talus: a pile of rocks at the bottom of a bedrock cliff, formed by falling and sliding of blocks of rock that detached from the cliff. Topset/foreset contact: the more-or-less horizontal boundary between topset and foreset beds in a delta. This boundary closely approximates the water level of the lake or ocean into which the delta was built. Jefferson Quadrangle, New Hampshire

Photos to accompany surficial geologic map

W. B. Thompson – August 2016

Figure 1. Glacial striations revealed by pencil rubbing of bedrock surface, on hillside NE of Jefferson village. The striation trends range from 145° (red pencil) to 153° (yellow pencil). Inferred ice flow was toward top of photo.

Figure 2. Pit face on hillside NNE of Jefferson village, showing about 15 ft of till (map unit Pt) overlain by 3 ft of gravelly diamicton. The till is very compact and probably was deposited as a lodgement facies at the base of the last glacial ice sheet. It has a silty-sandy matrix, shows fissile (platy) structure in the upper part, and contains striated stones. The overlying diamicton may be a glacial ablation deposit and/or the product of late-glacial mass wasting processes.

Figure 3. View looking south at moraine ridge (unit Pemc), east of Route 115A in Jefferson. Cherry Mountain appears in background.

Figure 4. View looking north at excavation showing longitudinal cross-section of moraine ridge (unit Pemc), just north of the moraine shown in Fig. 3.

Figure 5. View looking west along esker ridge (unit Pge) on lower SE flank of Pliny Mountain in Randolph. The cross-section of the ridge (center) is an overgrown bank that was excavated when building an old woods road.

Figure 6. Extremely coarse – yet very well rounded – gravel in exposure of the Israel Valley esker (unit Pge), SE of Route 116 in Jefferson. View looking NNW.

Figure 7. LiDAR image showing part of the Bunnell Brook valley in Lancaster. Note the arcuate headscarps of paleo landslides on the NW side of the brook in upper-right part of photo. An alluvial fan (map unit Qfb2 ) is seen along the brook farther down the valley, starting just SW of the deep shaded ravine (center to center-left part of image).

Figure 8. Alluvial fan gravel exposed in pit along Stag Hollow Brook, Jefferson. View looking NNE.

Figure 9. View looking NW (downstream) along the Israel River between Routes 115A and 116, showing modern flood plain (unit Ha) to left and slightly higher stream terrace (unit Qst) to right.

Figure 10. The broad Israel River flood plain and fresh sandy to gravelly channel deposits (Unit Ha) on the river bed. View looking SE (upstream) from Route 115A. The is seen in the distance.