Geology of High Point State Park

Transcription

1 J Geology of High Poin Sae Park Sussex Couny, New Jersey NJDEP R SEY GEOLOGICAL E S U Deparmen of Environmenal Proecion Land Use Managemen New Jersey Geological Survey W NE RVEY

2 STATE OF NEW JERSEY Richard J. Codey, Acing Governor Deparmen of Environmenal Proecion Bradley M. Campbell, Commissioner Land Use Managemen Lisa Jackson, Assisan Commissioner New Jersey Geological Survey Karl Muessig, Sae Geologis New Jersey Geological Survey producs are published by he New Jersey Geological Survey, P.O. Box 427, Trenon New Jersey. This bookle may be reproduced in whole or par provided ha suiable reference o he source of he copied maerial is provided. Addiional copies of his bookle and oher Survey repors, maps, and producs may be obained from: DEP Maps and Publicaions Sales Office P.O. Box 438 Trenon, NJ A price lis is available on reques. Cover Phoo: High Poin Monumen looking norheas across Lake Marcia. Phoograph by Ron Wie, 2002.

3 New Jersey Geological Survey Geology of High Poin Sae Park, Sussex Couny, New Jersey and Field Trip Guide by Ron W. Wie and Don H. Moneverde R SEY GEOLOGICAL E S U J W NE RVEY prined on recycled paper III

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5 INTRODUCTION High Poin Sae Park affords is visiors an excepional opporuniy o learn abou New Jersey s geology and is role in shaping he landscape. The park (fig. 1) lies on Kiainny Mounain in he glaciaed par of he Ridge and Valley physiographic province in norhern New Jersey. I consiss of abou 20 square miles of hilly fores, rocky ridge cress, and welands. Rock oucrops, smoohed by glacial erosion, are very abundan along he main ridge line of he mounain, bu in he wesern par of he park, bedrock exposures are sparse because he rock surface is covered by hick glacial sedimen. In his area, he many welands, ovalshaped hills, and rolling naure of he landscape are all producs of he las ice age. Kiainny Mounain forms a prominen norheas-rending ridge exending from Pennsylvania o he Shawangunk Mounains in New York. In places is coninuiy is broken by wind gaps, such as Culvers Gap, and waer gaps, such as Delaware Waer Gap. The High Poin Monumen, which lies a he norh end of he park on he summi of Kiainny Mounain, marks he highes poin in New Jersey a 1803 fee above sea level. Kiainny Valley lies eas of he park and i in urn is bordered on is easern side by a rugged upland called he New Jersey Highlands. Wallpack Valley, Wallpack Ridge, Minisink Valley, and he Pocono Plaeau are found o he wes. Shale, silsone, sandsone, quarzie, and conglomerae form he bedrock formaions in High Poin Sae Park. These sedimenary rocks are 460 o 400 million years old, and consis of maerial originally eroded from ancien lands and deposied as sedimen in sreams and seas ha once covered he area. These loose maerials were subsequenly buried by younger sedimens, and over millions of years hey evenually changed o solid rock. Repeaed uplif and subsequen erosion has exposed hese rocks. The srong norheas-rending ridge-and-valley opography in he High Poin area developed slowly, largely conrolled by he srucure of he underlying rocks and heir varying resisance o erosion. Kiainny Mounain, which is largely underlain by quarzie and 1

6 quarz pebble conglomerae, very ough rocks resisan o erosion, forms he highes land; whereas sofer rock underlies he valleys. During he pas wo million years, coninenal ice shees from he norh modified he landscape by deeply scouring valleys, wearing down and smoohing bedrock ridges, hills and slopes, and carrying away soil and loose rock miles 653 POCONO PLATEAU Culvers Gap Del Waer Gap NJ PA KITTATINNY Delaware R Delaware River MOUNTAIN VALLEY AND RIDGE HIGHLANDS Mill Bk CLOVE RD 84 SHAWAN- GUNK MTN Area of deail PA NJ NY RIVER RD NJ PIKE CO Delaware 521 PA Clove Bk 653 PARK R STEENY KILL RD STATE PARK BDY RIDGE CLOVE RD RD 1 23 Seeny Kill Lake 84 ORANGE CO SUSSEX CO Cedar Swamp High Poin Mon Lk Marcia NAT AREA BDY 519 RD GREENVILLE NY NJ NEW RD Shimers Bk PARK OFFICE Sawmill Lake Lile Fla Bk 650 Pine Swamp Big Fla Bk RD SAWMILL H I G H P O I N T Lake Ruherford (PRIVATE) 23 Clove Bk Bierskill High Poin Sussex Co NJ DECKERTOWN TPK Forked Bk Mashipacong Pond CRIGGER RD Parker Bk S T A T E P A R K NEILSON RD FILE RD 519 BRINK RD N 0 1 mile TO Figure 1. High Poin Sae Park and viciniy in norhern New Jersey. 2

7 BEDROCK GEOLOGY Rock Formaions High Poin Sae Park is underlain by hree sedimenary bedrock formaions ha rend norheas o souhwes (fig. 2). From oldes o younges hey are: 1) he Marinsburg Formaion, HIGH POINT STATE PARK BEDROCK GEOLOGY Sb Bloomsburg Red Beds-- (Silurian age) red shale, silsone and sandsone Ss Omh Bierskill Shawangunk Formaion-- (Silurian age) whie o gray quarzie and quarz-pebble conglomerae Marinsburg Formaion, High Poin Member-- (Ordovician age) gray shale, silsone and sandsone syncline or rough anicline or arch 650 Sb Pine Swamp Sb PARK Sb Big Fla Bk STATE PARK BDY RIDGE Sb Ss RD SAWMILL Ss RD 23 Sb Sawmill Lake Sb Ss Ss Ss Sb Lk Marcia PARK OFFICE Omh ORANGE CO SUSSEX CO High Poin Mon Seeny Kill Lake Lake Ruherford (PRIVATE) Omh Cedar Swamp Ss 23 Ss NY NJ Omh NAT AREA BDY Sb Parker Bk High Poin Sussex Co Ss Sb 650 Omh NJ N Ss 0 1 mile Omh Figure 2. Bedrock geologic map of High Poin Sae Park. 3

8 2) he Shawangunk Formaion, and 3) he Bloomsburg Red Beds (back cover). The Marinsburg Formaion underlies large pars of Kiainny Valley and a small area a Lake Marcia (fig. 1). The Shawangunk Formaion forms he higher ridges on Kiainny Mounain, whereas he Bloomsburg Red Beds underlie is wesern flank. The Marinsburg Formaion is Middle and lae Ordovician in age and records a hisory of sedimenaion in a deep ocean basin abou 462 o 450 million years ago. Marinsburg sedimens consis of sand, sil and clay ha were eroded from higher areas along an ancien coninenal margin and carried downslope by densiy currens o deeper pars of he ocean. Sedimens deposied in his manner are called urbidies. Each urbidie may conain five differen layers and each layer is defined by sedimen grain size and sedimenary srucures (fig. 3). The layers range from several inches o more han en fee hick. In New Jersey, urbidie sequences generally conain only he upper hree finer grained layers (fig. 3, layers C, D, and Figure 3. This diagram porrays he five pars of a classic urbidie. No all pars are presen every ime. The mos common urbidie in his par of New Jersey lacks par A and someimes B. The remaining pars, C, D, and E have a combined hickness of several inches. E D C B A Grain Size Mud Sandsil Sand 4 E) because he lower wo were eroded or deposied farher up he coninenal slope. The Marinsburg is divided ino he Bushkill, Ramseyburg, and he High Poin Members. The Bushkill Member is he oldes, consising of abou 1,500 fee of black shale ha was formed from clay deposied in he deepes pars of he ocean basin. Overlying he Bushkill Member and younger han i are he inerlayered shales, silsones and minor sandsones of he Ramseyburg Member. This layering and overall increase in grain size shows ha hese sedimens were laid down in a slighly shallower ocean closer o heir source. The Ramseyburg ranges from 2,400 o 5,000 fee in hickness in New Jersey and is abou 3,500 fee hick near he park. The High Poin Member is

9 as much as 4,500 fee hick, and is he younges and only member in he park. I consiss of alernaing hin sandsone, silsone, and shale. The sandsone layers are ypically coarse a heir base and finer-grained near heir op, a feaure called graded bedding. These layers are as much as 6 fee hick and make up he coarses par of he urbidie sequence (fig. 3). Pebbles of shale in heir base show ha he currens ha carried hem were powerful enough o rip up and erode some underlying sedimen. The upper surface of he Marinsburg Formaion is marked by he Taconic Unconformiy, a period of 20 o 30 million years during which he upper par of he formaion was uplifed and sripped by erosion. The Shawangunk Formaion was deposied on his surface; a sligh angular difference in bedding orienaion beween he wo formaions defines he unconformiy (fig. 4). Bedding Taconic unconformiy Shawangunk Formaion Bedding Hammer for scale Marinsburg Formaion Figure 4. Phoograph of he Taconic Unconformiy, exposed during he consrucion of Inersae 84, jus norh of he Park in New York. View is oward norh. Phoo aken by Jack Epsein, U.S. Geological Survey. The Shawangunk Formaion is of Middle Silurian age (approximaely 425 million years ago), abou 1,400 fee hick and consiss of inerlayered pebble conglomerae, quarzie, and some shale. The conglomerae mosly conains rounded pebbles of quarz wih lesser cher and shale in a marix of quarz sandsone. Sedimen 5

10 grain size becomes finer upward over several layers, forming repeaing sequences of conglomerae ha change from sandsone, o silsone and finally o shale. This grain-size composiion of he Shawangunk and is sedimenary srucures (fig. 5) show ha hese maerials were deposied by braided sreams in alluvial fans. A braided sream flows in several dividing and reuniing channels ha resemble a hair braid. Alluvial fans are large cone-shaped Ss (Shawangunk Formaion) bedding cross-bed bedding measuring sick (1 uni = 1 foo) Figure 5. Phoograph of cross-bedding in he Shawangunk Formaion a Sop 1. View is oward norh. The regional bedding surfaces are oulined and labelled. The cross-bed is clearly oulined in he rock by he more seeply inclined surfaces. deposis laid down by rivers flowing ou from mounainous areas ono low level plains. Mos of he Shawangunk sedimens were carried far ou on he plain and away from he mounains. The cross-bed orienaions in he Shawangunk Formaion (fig. 5) show ha he ancien rivers flowed in a norhweserly direcion. This demonsraes ha a mounain range o he eas was he source of he Shawangunk sedimens. Laer, and afer deep burial by younger maerials, a silica-rich fluid cemened he sand and gravel, forming he rock ha makes up he Shawangunk Formaion. This ough cemen also makes he rock very resisan o weahering and erosion. 6

11 The Bloomsburg Red Beds are of Lae Silurian age and conformably overlie he Shawangunk Formaion. The Red Beds are abou 1400 fee hick, consising of repeiively layered sedimens 3 o 9 fee hick. Each sequence of layers ypically has hree pars. The lower par consiss of gray o red, cross-bedded sandsone conaining pebbles. I gradually changes ino he middle par consising of very hinly layered, finer-grained sandsone or silsone ha locally conains race fossils. Cross-bedding in he sandsone layers shows ha waer currens flowed back and forh, suggesing ha he Bloomsburg sedimens were deposied under idal condiions along he coas of a large inland sea. The upper par consiss of red shale conaining mud cracks, roo races, and evidence of soil formaion. These feaures show ha he sedimen was exposed during shor periods when sea level was lowered and he shoreline rereaed seaward. The cycles of sedimenaion show ha sea level rose and fell many imes during deposiion of he Bloomsburg Red Beds. Regionally, fossil shells and marine animal burrows in he formaion also show a change in deposiional environmen proceeding from coninenal, o nearshore, o offshore oceanic environmens. Younger, carbonae rock, which lies ouside he park, conformably overlies he Bloomsburg Red Beds, indicaing a change o clear, warm shallow seas. Srucure of he Rocks Compressional or pushing forces caused by he collision of coninenal plaes hundreds of millions of years ago formed folds, fauls, joins, and cleavage in he rocks ha underlie he park. Folds form by compressive force, similar o pushing wo ends of a piece of paper ogeher. The arches and roughs ha form are called aniclines and synclines respecively. Fold magniude varies in each formaion, bu in he park i is on he order of several hundred fee (fig. 6). Generally, folds canno be seen a an individual bedrock oucrop. One needs o walk across he rock and noe he slow change in he dip of he beds from souheas o norhwes. A faul is a fracure or group of fracures in rock where one side has moved pas he oher. Such breaks form when rock is squeezed or pulled apar. An offse of sedimenary layering marks he locaion of a faul and helps o deermine he rock s movemen direcion. Fauls ha parallel layering are harder o discern. A faul commonly exhibis linear grooves ha show he direcion of 7

12 EXPLANATION Sb Bloomsburg Red Beds Shawangunk Ss Formaion Marinsburg Fm., Omh High Poin Member Taconic unconformiy bedding Lake Marcia High Poin Monumen FEET 2000 anicline syncline anicline syncline land 2000 surface Ss 1000 Sb Sb 1000 Ss Ss SEA LEVEL SEA LEVEL Omh Omh Omh mile FEET Figure 6. Regional crosssecion hrough Lake Marcia from he norhwes (lef) o he souheas (righ). The view, aken from he Lake Marcia beach, faces norh oward he monumen. moion. These grooves form where bumps on he faul surface slide pas and gouge he opposing rock surface. Quarz veins are also common in fauls and heir alignmen is similar o ha of he grooves described above. Fauls cu he hree rock formaions in he park; all are small, have minor offses, and are no longer acive. They are mos common in he brile rocks of he Shawangunk Formaion. Joins are he mos common srucural feaure in rocks (fig. 7). They are fracures, bu unlike fauls, hey show no evidence of movemen parallel o heir common surface. Joins form where pulling or pushing forces caused he rock o break. Joins may cu across a whole oucrop or only an individual bed, and hey commonly form in parallel or subparallel arrays called join ses. Several differen ses may occur in large areas, and hey record he regional sresses ha caused he fracuring. Ground waer moves chiefly hrough fracures such as joins, so join analysis helps us o undersand ground-waer flow. Fine-grained rocks such as shale and slae spli along closely spaced parallel planes called cleavage. Cleavage forms under compressive pressure in rocks enriched in clay minerals. Fine- 8

13 join bedding Ss (Shawangunk Formaion) join join measuring sick (1 uni = 1 foo) Figure 7. Phoograph of subverical joins in a souh-facing oucrop of he Shawangunk Formaion. Bedding is dipping slighly o he eas (righ). grained rocks develop cleavage more readily han coarse-grained rocks because hey conain more clay. This allows he rock o be spli ino fla producs like chalk boards. The Marinsburg shales exhibi he bes-formed cleavage in his region and hey have been used for roofing slae and paving sone. Slae is shale in which he cleavage is highly developed. Therefore, he shales of he Marinsburg are beer ermed slaes. Silsones and sandsones in he Marinsburg also exhibi cleavage, bu i is generally no as exensive and less closely spaced (fig. 8). Poorly developed cleavage occurs locally in he Bloomsburg Red Beds and he Shawangunk Formaion. 9

14 Omh (Marinsburg Formaion, High Poin Member) 1 inch in diameer cleavage vein bedding Figure 8. Phoograph of cleavage in he slaey member of he Marinsburg Formaion looking souh (eas o he lef). Very closely spaced cleavage surfaces, almos paper hin, can be seen dipping o he eas. Subverical veins, formerly open fracures, are filled by quarz, a whieish mineral. Teconic Hisory Kiainny Mounain is par of he Appalachians, a long mounain chain ha sreches from Alabama o Newfoundland. Is hisory includes hree periods of coninenal sreching and collision ha all involved folding and fauling. In norhwesern New Jersey mos of he folds, fauls, joins and cleavage formed during hree periods of mounain building. Abou 650 million years ago, during he Lae Proerozoic, he granie and gneiss now making up he New Jersey Highlands were par of an ancien coninen called Rodinia. Abou 540 million years ago, powerful econic forces began pulling he landmass apar. As he coninenal crus hinned and sreched, elongae rif valleys were formed. As ime wen on, he rifs widened and deepened, and flooded wih sea waer, evenually forming new oceanic basins. Finally, econic aciviy along he coas subsided. Carbonae sedimens were deposied along an easward facing shoreline of a warm shallow sea unil abou 480 million years ago. During his ime, abou 3000 fee of maerial accumulaed; i now makes up he carbonae rock ha underlies 10

15 o o 74 o PA NY EXPLANATION Mesozoic rif basins 76 o High Poin Carboniferous and Permian rocks 41 o NY NJ Silurian and Devonian rocks 41 o Cambrian o middle Ordovician rocks of he early Paleozoic coninenal shelf Early Cambrian o middle Ordovician ranspored rocks of ancien Norh American coninenal slope and rise o Pa NJ 0 16 miles Proerozoic meamorphic and pluonic rocks Figure 9. Regional geologic map of he area surrounding High Poin Sae Park. par of Kiainny Valley. Abou 460 million years ago he ocean basin began o close and a period of mounain building, called he Taconic Orogeny, began. During is iniial sages, he Norh American plae collided wih several smaller plaes. This collision caused uplif and erosion of he carbonae rocks. A downwarping followed ha submerged he land beneah he sea. Folding, fauling and a wesward pushing and sacking of he rocks and sedimens in he collision zone formed a mounain chain. Over ime he mounains were lowered by erosion, he weahering producs of clay, sil, and sand were carried wesward by rivers and ocean currens o a deep ocean basin. These maerials hickened, compaced and became he shale, silsone and sandsone of he Marinsburg Formaion. Following deposiion of he Marinsburg sedimens, he enire region was again uplifed and he landmass again slowly eroded. This period lased abou 25 million years and marks he Taconic Unconformiy, a regional surface ha displays evidence of exensive erosion. Evenually, a wesward facing coasal plain formed a he base of he mounains ha became covered by sream deposis. These deposis make up he Shawangunk Formaion. As sea level rose slighly, sedimens laid down in muddy idal flas and shallow marine waers ha now make up he Bloomsburg Red Beds were deposied on he Shawangunk sedimens. As he coninenal margin furher subsided, seas evenually covered he Bloomsburg Red Beds. Carbonae maerials were deposied in his calm shallow-marine environmen. These carbonae rocks now lie jus wes of he park. 11

16 Beween 410 and 380 million years ago a second period of mounain building occurred. This even, called he Acadian Orogeny, also involved several smaller coninenal plaes colliding wih he Norh American plae. This orogeny, responsible for New England s major srucural feaures, is no represened in he rocks in High Poin Sae Park. A hird period, called he Alleghany Orogeny, occurred beween 330 and 250 million years ago. Inense folding and fauling of he park s rocks mark his collision of he Norh American coninen wih he African coninen. EVOLUTION OF REGIONAL LANDFORMS The landscape around High Poin Sae Park was shaped by many geologic processes acing hroughou millions o ens of millions of years. These processes included uplif and subsidence of he earh s crus, physical and chemical weahering, erosion by sreams, and mass wasing. Some geologiss believe ha he presen landscape had is beginnings in Permian or Triassic ime when a large river sysem flowed wesward oward he coninenal inerior (he area now drained by he Mississippi River and is ribuaries). When coninenal rifing opened he Alanic Ocean more han 200 million years ago, in lae Triassic ime, newly formed sreams along he coas worked heir way inland and capured pars of he inland drainage. As ime passed, sreams flowing over weaker rock cu valleys faser and deeper han hose flowing over ough, harder rock. Because bels of rock rend norheasward in norhwesern New Jersey, drainage developed along norheas- o souhwes rending bels of weaker rock. In some places, hard, resisan rocks were weakened by fauls or numerous joins. Sreams cu hrough hese resisan ridges a heir weakened poins and formed feaures like Delaware Waer Gap and Culvers Gap. Oher geologiss hink ha he ancesral Appalachian Mounains were worn low and subsequenly covered by a hick layer of coasal plain sedimens more han 100 million years ago during he Mesozoic Era. Newly formed sreams, which flowed souheasward following he seaward slope of he land, cu heir drainage inland from he Alanic Ocean. Following a lenghy period of erosion, he underlying folded and fauled rocks of he Appalachians were exposed and sreams began o adjus o he rock s srucure. Waer gaps were eroded in places where souheas flowing rivers firs encounered he resisan rocks ha make up he modern uplands such as Kiainny Mounain. 12

17 The principal landscape feaures of he park probably formed during he lae Teriary period (10 o 25 million years ago). During his ime, erosion and valley cuing acceleraed when sea level fell due o he growh of he Anarcic ice shee, and possible uplif of he earh s crus. Rejuvenaed sreams eroded he old land surface, deepening valleys and waer gaps and furher adjusing heir courses along bels of weak rock. I was probably during his ime ha a sream flowing in wha is now Culvers Gap was inerceped and capured by a ribuary of he Delaware River. THE ICE AGE Regional Hisory During he Pleisocene Epoch (2 million o 10 housand years ago) ice shees advanced over norhern New Jersey a leas hree imes (fig. 10). From oldes o younges, hese glaciaions are named he pre-illinoian, Illinoian, and lae Wisconsinan. Glaciers are large bodies of ice ha form over long periods from he gradual buildup of compaced and recrysallized Belvidere I Warren pi lw Hunerdon area of deail Sussex Somerse Mercer High Poin Sae Park Morris Passaic Middlesex Essex Union Perh Amboy Monmouh Bergen Hudson Saen Island Figure 10. Limis of glaciaions in New Jersey. The race of he lw limi generally marks he Terminal Moraine. Key: lw - lae Wisconsinan, I - Illinoian, and pi - pre- Illinoian. 13 snow. Evenually, he ice becomes hick enough o flow under he sress of is own weigh. Ice shees are hick glaciers ha cover large pars of coninens. In Norh America he Laurenide and Cordilleran ice shees grew o enormous sizes. I is esimaed ha heir ceners were as much as 10,000 fee hick. A High Poin, he ice may have been 2000 fee hick when he Norh American ice shees were a heir maximum size. The Norh American ice shees were cenered in he subarcic regions of Canada and grew and spread ouward during periods when he norhern hemisphere was

18 colder han i is now. Curren ideas are ha small changes in he earh s orbi, il of is axis, direcion of ocean currens and sorms, and volcanic dus in he amosphere may have all conribued o global cooling. The geologic record shows ha he growh and decay of coninenal ice shees in he norhern hemisphere was cyclic. In New Jersey, he climae varied from arcic or boreal during glacial periods o emperae or subropical during inerglacial periods. Today we are considered o be in an inerglacial sage. A precise age of he oldes glacial deposis is uncerain. Their exensive weahering and poor preservaion sugges hey were laid down more han 800,000 years ago. Laer, during he Illinoian sage abou 150,000 years ago, an ice shee again covered norhern New Jersey. Mos recenly, New Jersey was glaciaed during he lae Wisconsinan subsage, abou 20,000 years ago. Each ice shee modified he land scape. Valleys underlain by weak rock were widened and deepened; bedrock ridges, hills, and slopes were slighly worn down and sreamlined, and mos surface maerials were eroded. Rocks, gravel, sand, sil, and clay enrained in he ice shees were deposied as ill, an unsored mixure of clay- o boulder-sized maerial. This maerial was laid down on he bedrock surface in shees, in sreamlined hills called drumlins, and in ridges laid down along he former edge of he ice shee called moraines. Sraified sedimen consising of sored and layered gravel, sand, and sil was deposied by glacial melwaer sreams in valleys ha drained away from he glacier and in glacial lakes. The harsh, cold climae immediaely souh of he ice shees enhanced erosion of surficial sedimen by mass wasing, and acceleraed he physical weahering of bedrock, largely by fros shaering. In conras, emperae and subropical climaes during inerglacial periods lessened raes of physical weahering, bu increased raes of chemical weahering, which led o he formaion of hick decomposed bedrock. Local Hisory High Poin Sae Park lies enirely wihin he limi of he las glaciaion and only glacial deposis (fig. 11) and erosional feaures associaed wih he lae Wisconsinan ice shee are preserved here. Older glacial deposis and feaures were buried beneah younger glacial sedimen or were eroded during he las glaciaion. The lae Wisconsinan advance of ice ino norhwesern New Jersey consised of ice lobes iniially moving souhwesward down Minisink and Kiainny Valleys. In ime, he ice became hick enough o flow over Kiainny Mounain and, urning souh, i flowed across he 14

19 s m HIGH POINT STATE PARK SURFICIAL GEOLOGY swamp-- low area of waerlogged ground Augusa (ma), Monague (mm) and Seeny Kill (msk) moraine-- ridge of ill deposied a he glacier s erminus hick ill-- unconsolidaed mix of clay, sil, sand, gravel and boulders greaer han 10 fee hick hin ill and bedrock-- ill less han 10 fee hick, rock oucrops, and weahered rock msk PARK RIDGE STATE PARK BDY RD msk s 23 Seeny Kill Lake ORANGE CO SUSSEX CO Cedar Swamp Lk Marcia s High Poin Mon NY NJ NAT AREA BDY mm 650 Bierskill mm s mm Pine Swamp s s s s Parker Bk s ma s s s s ma msk s ma s s s ma s ma s s Big Fla Bk s 650 RD SAWMILL Sawmill Lake s PARK OFFICE Lake Ruherford (PRIVATE) s 23 High Poin Sussex Co NJ N 0 1 mile ma Figure 11. Surficial geologic map of High Poin Sae Park. region s souhweserly opographic grain. The Terminal Moraine, which lies 30 miles souh of he park (fig. 10), marks he farhes advance of he ice shee. However, in a few valleys, sublobes of he glacier exended as much as a mile souh of he Terminal Moraine. During deglaciaion, he edge of he ice shee hinned and is flow became more conrolled by he souhweserly rend of he larger valleys. The Kiainny and Minisink Valley ice lobes rereaed 15

20 NY PA N Kiainny Mn Pocono Plaeau Caskill Mounains area of deail Highlands Piedmon Coasal Plain Hudson-Wallkill Lowlands NY NJ EXPLANANTION large souh-draining valleys glacial lake basin uplands direcion of glacial-lake drainage KITTATINNY Delaware River Belvidere 2 3 MA CT 0 20 miles KITTATINNY VALLEY JENNY JUMP MOUNTAIN 5 Francis Lake WALLPACK Lake Oxford 6 7 RIDGE MOUNTAIN Lake Owassa Culvers Lake Lake Newon Lake Swarswood Lake Sillwaer Lake Big Springs Lake Millbrook Lake Wallkill Augusa spillway Lake Beaver Run Lake Peques 1 8 HIGH POINT STATE PARK N Y N J Lake Spara 3 N 0 5 miles POCHUCK MTN Lake Hamburg Lake Norh Chruch 4 ICE-MARGINAL POSITIONS 8 Sussex margin 6 Augusa margin 5 Culvers Gap margin 4 Spara margin 3 Franklin Grove margin 1 Terminal Moraine ICE-MARGINAL POSITIONS (local names in Delaware Valley) 8 Tri Saes 7 Millville 6 Monague 5 Dingmans Ferry 3 Sand Hill Church 2 Zion Church Figure 12. Ice margins of lae Wisconsinan age showing successive posiions of he ice fron as i rereaed norheasward, locaion of large glacial lakes, and exensive valley-ouwash deposis in norhwesern New Jersey. gradually o he norheas. However, a imes he edge of he ice lobes remained saionary, and in a few insances readvanced souhward a few miles (fig. 12). Deglaciaion was probably riggered by warming emperaures ha meled ice a he glacier margin faser han i was replaced by flowing ice, and by a decrease in he formaion of new glacier ice due o reduced precipiaion on he ice shee. During periods when he glacier margin remained saionary, sand and gravel laid down by melwaer sreams buil up a and beyond he glacier margin in sream valleys and glacial lakes in 16

21 Minisink, Wallpack, and Kiainny Valleys (fig. 12). Addiionally, end moraines were deposied a he glacier s erminus. Boh he ice-marginal pars of he melwaer deposis and end moraines mark he former edge of he ice shee. Mapping hese ice recessional posiions enables geologiss o reconsruc he geomery and rerea hisory of he ice shee. The Augusa margin, which runs hrough High Poin (fig. 12), is delineaed by he Augusa and Monague moraines. The coninuiy of he moraines, and he size and exen of melwaer deposis laid down in nearby valleys souh of he Augusa margin show ha he glacier s erminus mainained a nearly consan posiion for more han a hundred years. Erosion by Ice Feaures carved in bedrock by moving glacial ice are numerous in he park. They include sriaions, crescenic marks, polished bedrock, and plucked oucrops. Sriaions are linear scraches and grooves cu in bedrock by overriding ice ha show he direcion of glacial movemen. They formed in places where hard sones, frozen o he boom of he glacier, scraped across he underlying bedrock. Sriaions are also found on sones ha have been glacially ranspored. Crescenic marks, which include gouges, fracures, and chaer marks, are cracks and chips in he rock surface made when sones a he glacier s base exered grea pressure on he underlying rock. Sriaions and crescenic marks in he park show ha he glacier flowed S70 o W o due wes. These feaures were made near he edge of he Kiainny Valley ice lobe when he fron of he ice was rereaing. I is likely ha souherly oriened sriaions, made earlier when he ice was much hicker and is margin far souh of High Poin, were subsequenly removed by glacial erosion. Oher forms of glacial erosion include polishing and plucking. Polishing occurred where sand and sil, frozen o he glacier s base, slid over rock. Like sandpaper smoohing a piece of rough wood, he rock surface becomes highly smoohed and polished. Plucking occurred where rock fragmens, fracured and loosened from pressure exered by he weigh of he over riding glacier, were broken off. Generally, he fragmens, some as big as boulders, are removed from he downsream side of he oucrop. In exreme cases, he processes of abrasion and plucking can impar a whaleback shape o an oucrop, also called a roche mouonnée. 17

22 Glacial Deposis All of he deposis in he park laid down direcly by or from glacial ice are called ill. Till, a nonsored mixure of clay o bouldery sized maerial, covers he bedrock surface in mos places, excep he rocky cres of Kiainny Mounain and a few seep hillslopes. Where i is hin, he underlying bedrock opography shows hrough. Thicker ill subdues and buries his irregu lar surface, and in many places compleely hides i. Till in he park is ypically a compac, yellowish-brown, brown, or ligh olive brown sily sand consising of a mixure of quarz sand, rock fragmens, feldspar, sil, and clay. Subangular o subrounded sones of quarz pebble conglomerae, quarz ie, red sandsone, gray sandsone, and red shale may make up as much as 20 percen of he deposi by volume. Many of hese are sriaed. This maerial is called lodgemen ill and was deposied pick (for scale) shovel (for scale) basal ill 1: poorly sored, nonsraified mix of clay- o boulder-sized maerial. 1 basal ill 2 flowill 3 planar beds of gravel and sand 4 inclined beds of sand and some gravel 5 laminaed beds of sil, clay, and very fine sand bedrock 1 3 dela melwaer sream 4 dela moraine lake level lacusrine fan lake boom 1 2 planar beds 3 of sraified gravel and sand: deposi of a glacial melwaer sream. 5 GLACIER mile verical exaggeraion x20 1 debris bands Figure 13. Block diagram showing he deposiional seing of glacial sedimens wih phoo inses of ill and ouwash. 18