,the ,geology of ,,mt4 ,,mansfield ,,state ,,forest ,by ,,robert ,a4 ,,christman ,,department ,,of ,,forest ,,and ,,parks ,perry ,h4 ,merrill1 ,director ,,vermont ,,development ,,commission ,,vermont ,,geological ,,survey ,charles ,g4 ,doll1 ,state ,geologist #aief ,illustration3 ,cover photo3 ,smugglers ,notch looking northeast from the top of ,mount ,mansfield4 ,,geology ,,of ,,mount ,,mansfield ,,state ,,forest ,by ,,robert ,a4 ,,christman ,,introduction ,included within ,mount ,mansfield ,state ,forest are ,mount ,mansfield1 ,smugglers ,notch and a number of the mountains of the ,green ,mountain range to the northeast and southwest of these famous landmarks4 ,because much of the area is easily accessible by trails1 ski lifts1 and roads 7see the index map of ,figure #a71 the visitor has ample opportunity to observe the minerals1 rocks1 and mountains4 ,undoubtedly1 these observations have provoked questions which1 for lack of sufficient information1 have gone unanswered in the mind of the observer4 ,in the hopes of remedying this situation--a very grievous situation in the eyes of a geologist--this brief geologic pamphlet has been written to help the visitor to the ,state ,forest obtain a greater appreciation of the handiwork of nature4 ,to begin with1 geology can be defined as the study of the history of the earth as recorded in the rocks4 ,it includes the study of minerals1 rocks1 fossils1 the structure of the rocks1 and the forms of the land4 ,although only a few have been fortunate enough to choose this subject as a profession1 the field is wide open for amateurs4 ,this report is divided into four sections4 ,the first describes the rocks2 the second deals with the detailed structure of the rocks and the mountains2 the third treats the glacial history of the area2 and the fourth part describes the geology that may be seen at various localities within the park4 ,,description ,,of ,,the ,,rocks ,introduction ,with a few exceptions1 the rock found in ,mount ,mansfield ,state ,forest is a mica-albite-quartz schist4 ,this name indicates that it is a metamorphic rock#a of a particular composition and texture as described in the following paragraphs4 ,the schist forms the cliffs at ,smugglers ,notch and the bare-rock faces exposed along the crests of the mountains and elsewhere4 ,it varies slightly in appearance because of variation in the proportions of the different mineral constituents4 ,illustration3 ,figure #a4 ,index mapping showing location of ,mount ,mansfield ,state ,forest4 ,origin of the schist ,an understanding of the origin of the schist is fundamental to understanding the geology of the ,mount ,mansfield area4 ,many million years before the formation of the ,green ,mountains1 northwestern ,vermont was covered by a shallow sea into which fine-grained sediments were transported by the ancient rivers4 ,as these sandy and shaly deposits accumulated on the bottom of the sea1 they were buried by progressively younger sediments of different types4 ,many of these sedimentary layers contained shells of the animals that lived and died in these seas1 with the shell remains of the older generations occurring in the bottom layers4 ,by the time the sea had retreated1 the older sediments were deeply buried beneath the younger sediments4 ,during a period of mountain-making1 these materials were subjected to high pressures and high temperatures4 ,physical-chemical changes took place within the sediments causing recrystallization to form the mica-albite-quartz schist4 ,in other words1 under conditions of heat and pressure the rocks became plastic and the elements which were dispersed through the sediments as sand and clay minerals reorganized into different and larger mineral grains4 ,it is probable that some material was added to the rocks and some was removed by hot solutions migrating through the rocks4 ,the overlying younger sediments were also converted to metamorphic rocks4 ,because the crystallization of the minerals occurred under the influence of pressure1 platy minerals developed with their long dimensions at right angles to the pressure4 ,thus1 the resulting rock developed a layered appearance by the parallel arrangement of the minerals4 ,where this layering or banding1 which is called foliation1 is coarse1 the metamorphic rock is a gneiss2 where it is fine but pronounced1 the rock is called a schist4 ,if the original rock was a limestone or sandstone1 the metamorphic product is marble or quartzite1 respectively4 ,in the process of1 or following the formation of the schists1 the rocks were crumpled and folded by continued pressure4 ,during the #chj million years following the metamorphism and folding1 this area has been above sea level and has been subjected to erosion4 ,at various times the area was uplifted vertically which resulted in continued erosion of progressively older rocks until the present day when the overlying rocks have been removed to expose the mica-albite-quartz schist4 ,age of the mica-albite-quartz schist ,some readers may wonder how the age of metamorphism can be stated so specifically--#chj million years seems like a long period to be determined beyond a guess4 ,such a determination is based on a number of different factors4 ,sedimentary rocks can be placed in their general age sequence by their physical relationships--the rocks deposited on top must be the youngest4 ,a study of the fossils of successive layers shows that they occur in a definite sequence with the simpler forms in the oldest layers and generally the more complex ones in the youngest layers4 ,on the basis of the fossil evidence and the physical relations1 the geologic sequence of the layers can be established for any given area and their relative age can thus be indicated on the geologic time scale4 ,usually such sequences are established for rather large areas as1 for example1 northern ,vermont or eastern ,new ,york ,state4 ,in addition1 actual age determinations can be made for some rocks4 ,many igneous rocks contain traces of uranium which has been decomposing at a known rate since its formation4 ,by comparing the remnants of uranium with the decomposition products1 one can assign an approximate age in terms of years to the igneous rock4 ,by observing the relationship between the dated igneous rock and any sedimentary rocks in contact with it to determine their relative ages1 it may be possible to assign an approximate age to the sedimentary rock and the fossils contained within it4 ,the general age of the original constituents of the mica-albite-quartz schist of the ,green ,mountains can be determined only by comparison to other rocks that can be dated4 ,any fossils present originally were destroyed during metamorphism4 ,igneous rocks containing uranium do not occur with the schist4 ,however1 elsewhere in ,vermont1 one can determine that the schist lies beneath rocks containing fossils of ,ordovician age and lies above pre-,cambrian rocks known to be more than #ejj million years old4 ,the ,cambrian and ,ordovician periods on the geologic time scale are the oldest periods containing abundant fossils4 ,the period of the metamorphism is based on evidence at other localities where unfolded rocks of known age lie over folded rocks4 ,on the geologic time scale the mica-albite-quartz schist on ,mount ,mansfield is said to be ,cambro-,ordovician in age1 which may be from #chj to #ejj million years ago4 ,in order that the geologist can talk about the sequences of rocks1 layers having a similar age and appearance are assigned a formation name4 ,the schists on ,mount ,mansfield closely resemble schists in southern ,vermont which belong to the ,pinney ,hollow formation4 ,however1 because they can not be traced directly1 it is possible that the two sequences are not exactly equivalent4 ,for this reason some geologists assign the rocks in this area to the ,camels ,hump formation which has been named after their abundant occurrence on ,camels ,hump ,mountain1 south of the ,mount ,mansfield ,state ,forest4 ,although it would be geologically correct to use these formational names1 they will be omitted in favor of continued use of the name 8mica-albite-quartz schist40 ,the formation which lies over the mica-albite-quartz schist may be seen in the vicinity of the village of ,stowe where the rocks are either a black1 shiny schist or a fine-grained green schist4 ,the formation which lies under the mica-albite-quartz schist is not exposed in the ,mount ,mansfield area4 ,description of the schist ,as the name implies1 the mica-albite-quartz schist contains the minerals mica1 albite1 and quartz4 ,these mineral constituents are found in all the schists in the area4 ,other minerals may be locally abundant or present in small amounts4 ,when the schist is examined without a hand lens or microscope1 mica appears to be the most abundant mineral4 ,it occurs as small colorless to white flakes which sparkle and shine in the sunlight4 ,you may recognize this mineral as the one that is sometimes sold as artificial snow at ,christmas time4 ,its species name is muscovite1 and it has a chemical composition of ,k,al7,al,si7,o7,,oh74 ,muscovite is found in various proportions in most of the rocks in the area4 ,it is a deceptive mineral upon which to make a percentage estimate because it appears to be more abundant than it actually is4 ,in most of the rocks it comprises less than #ej per cent of the minerals4 ,biotite is the other important member of the mica group and is distinguished from muscovite by its black or dark brown color4 ,biotite occurs in minor proportions in the rocks of the area1 being most abundant on the western slope of ,mount ,mansfield4 ,like muscovite1 biotite occurs as small flakes with smooth flat surfaces4 ,the orientation of the mica flakes accounts for the pronounced layering of most schists4 ,all of the flakes are parallel and when folded and crumpled they give the rock its structure4 ,where the muscovite is most abundant1 breakage along planes rich in mica produces smooth1 shiny surfaces which may give the rock a slippery appearance4 ,the layers rich in mica may show in a rather perfect manner the small-scale folding of the schist4 ,albite and quartz are also important constituents of the schists4 ,together they are more abundant than mica in the average schist on ,mount ,mansfield but because they are not so 8showy0 they are more easily overlooked4 ,both minerals are white and granular4 ,quartz1 which consists of silica or ,si,o1 is the principal constituent of most beach sands4 ,in the typical mica schist1 quartz is glassy in appearance and occurs as small rounded or irregular grains without plane surfaces4 ,albite is a variety of plagioclase feldspar having the composition of ,na,al,si,o4 ,it has a white chalky appearance and occurs in small equidimensional grains bounded by flat surfaces which break along plane surfaces that reflect light in certain positions4 ,on the west side of ,mount ,mansfield some of the rocks contain so much albite and so little mica that the rock is granular in appearance4 ,chlorite1 variety pennine1 is an important mineral constituent of some of the schist4 ,chlorite is characterized by its green color and small amounts are responsible for giving a greenish cast to much of the schist4 ,like mica it occurs as thin sheets which reflect the folding of the schist4 ,garnet and magnetite are locally abundant minerals in the schist4 ,garnet occurs as pink to red grains ranging from pin point to pea size4 ,most of the grains are rounded although a few occur as equidimensional crystals which have twelve equally developed faces4 ,garnet has a semitransparent1 glassy appearance and is harder than a knife blade4 ,magnetite occurs as bluish-black metallic masses with about the same size range as the garnet4 ,although most are rounded masses1 crystal faces are developed on some4 ,perfectly developed crystals occur as octahedrons which is the form consisting of eight faces1 as two four-sided pyramids with their bases together4 ,the larger grains of magnetite have sufficient magnetic power to attract or deflect a compass needle4 ,the garnet and magnetite usually do not occur together1 but each may form localized concentrations as lenses or layers in the schist4 ,in smaller amounts1 usually visible only with a hand lens or microscope1 the schist also contains a green mineral called epidote1 a white mineral apatite1 and an elongated black mineral called tourmaline4 ,locally1 as on the ,nose ,dive ski run above the ,toll ,road on ,mount ,mansfield1 slender needles of tourmaline are visible in the schist4 ,when a piece of rock is sawed and ground to a thickness of #j4jc millimeters1 many of the minerals that appear opaque are found to be transparent4 ,by their color and their optical properties the minerals can be accurately identified4 ,on the basis of the amount of each present the mineral and chemical composition of the rock can be determined4 ,figure #b shows the appearance of a thin section of the mica-albite-quartz schist from the ,forehead of ,mount ,mansfield4 ,the parallel orientation of the mineral grains is apparent even though the photomicrograph represents a very small area of the schist4 ,illustration3 ,figure #b4 ,photograph taken through a microscope at a thin section of the schist4 ,the white and gray grains are quartz and albite and the dark colored elongate grains are either muscovite or chlorite4 ,the magnification is about one hundred times normal size4 ,even at this scale1 the layering of the minerals is clearly visible4 ,other varieties of the schist occur less abundantly in the area4 ,these contain the same minerals as the mica-albite-quartz schist but in different proportions4 ,if the mica is most abundant1 as it is locally on ,mount ,mansfield1 the schist may be smooth or highly crinkled and have a very shiny appearance4 ,if the albite is most abundant the schist is more uniform and granular in appearance and the rocks are more massive4 ,small scale folding is usually absent4 ,such albite schists occur on the west side of ,mount ,mansfield1 particularly along the lower part of the ,maple ,ridge ,trail and in the cliffs south of the ,forehead along the ,long ,trail4 ,if the quartz is most abundant1 but mica and albite are present in considerable quantities1 the rock may have a granular1 layered appearance4 ,locally some of the rocks consist almost entirely of quartz and are classified as quartzite4 ,these rocks have a dense1 fine-grained1 sugary appearance and generally are gray to bluish gray in color4 ,they are hard rocks and often form minor ledges in cliff exposures or are the resistant rock at the top of small waterfalls in some of the creeks4 ,most of the quartzite in the area occurs in narrow layers less than a foot thick4 ,although these layers cannot be traced1 they are most abundant on the east side of ,mount ,mansfield at various localities about one-third of the way up the mountain4 ,at places1 vein-like masses of glassy1 milky white quartz occur in the schist4 ,in these1 the quartz is massive and without evidence of individual grains and is often fractured unevenly4 ,the quartz occurs as localized lenses in the schist1 particularly at the noses of the folds4 ,the small1 white boulders of quartz of this type are conspicuous along some of the trails4 ,a special and somewhat unique type of rock occurring at ,sterling ,pond is described in the description of ,spruce ,peak and ,sterling ,pond4 ,structure of the mountain and the rocks ,the position of the ,green ,mountains is a function of the structure of the rocks and their resistance to erosion4 ,at the same time that the mica-albite-quartz schist was being developed under conditions of heat and pressure the region was tightly folded by the same forces4 ,it is likely that this folding continued after the metamorphism during the declining stages of mountain-making4 ,this period of mountain-building probably raised the rocks to a higher level but it was the later repeated uplifts and erosion of the overlying rocks which finally produced the present mountain topography4 ,it is postulated that the folding and crumpling of the schists were accompanied by a westward movement of large masses of rock4 ,that is1 segments of the earth's crust are believed to have been pushed westward by pressure from the east4 ,thus1 it is believed by many geologists that the rock which now occurs in the ,green ,mountains may have been derived in early times from an area ten to forty miles to the east4 ,the basic structure of the ,green ,mountains is an anticlinorium1 a large complex fold4 ,an anticline is an upward fold in which individual rock layers if traced through the structure have a shape similar to that of an arch2 the opposite structure is a syncline in which the individual layers are shaped like a trough or basin4 ,an anticlinorium is a large anticline upon which are superimposed many smaller anticlines and synclines4 ,figure #c is a diagrammatic sketch showing the relation of the topography to the structure of the rocks in the ,mount ,mansfield area4 ,the structure of the rocks is reflected in the topography of ,mount ,mansfield1 but such correspondence is not necessary1 for the form of any hill or mountain is a function of its erosional history and resistance of the rock to erosion4 ,in some folded areas1 the rock in the trough of a syncline is so resistant to erosion1 that it persists in hills or mountains after neighboring anticlines have been more deeply eroded to form valleys4 ,illustration3 ,figure #c4 ,diagrammatic sketch showing the relation between the topography and the structure of the ,green ,mountains in the ,mount ,mansfield area4 ,the section has been drawn to approximately pass through ,the ,chin1 ,smugglers ,notch1 ,spruce ,peak and ,sterling ,pond1 and looking ,n #bj ,w4 ,,the ,,chin ,,smugglers ,,notch ,,spruce ,,peak ,,sterling ,,pond ,the smaller folds are like 8little fleas on bigger fleas on bigger fleas0 in that many little folds may be superimposed on larger ones4 ,these anticlines and synclines range in amplitude from fractions of an inch to thousands of feet4 ,many are miniature anticlinoria themselves and could be used as scale models of the structure of the entire mountain range4 ,the small folds1 or crenulations1 in the schist have weathered differentially so that the more resistant layers stand out in relief1 emphasizing the shape of the folds4 ,the photograph in ,figure #d shows the small-scale folding4 ,it will be noted that the anticlinal folds are asymmetrical with the west side dipping more steeply than the east side4 ,if a comparison is made between the structure of the mountain and that of an asymmetrical arch1 to carry the simile one step further1 it may be imagined that the axis of the arch may be either horizontal or inclined4 ,the chances that it is inclined are much greater than the chance that it is exactly horizontal4 ,thus1 most anticlines or anticlinoria are inclined along their axes and the amount of the dip of the line connecting the points along the crest of the fold is called the plunge4 ,most of the folds in the ,mount ,mansfield area plunge about ten degrees to the south4 ,this plunge is expressed in the dip of the crests of the minor folds1 particularly in the crenulation of the mica layers4 ,viewed at a distance the trace of the fold-crests form a series of parallel lines on the smooth mica-rich surfaces4 ,this type of structure is called the lineation and is expressed on the geologic map by small arrows4 ,the dominant lineation is north-south4 ,although ,figure #e is a sketch of a small fold showing the different structural elements1 it might be taken as a diagrammatic sketch of the regional structure4 ,evidence that the structure of the rocks is even more complex is shown locally by the presence of east-west lineations4 ,the intersection of this secondary lineation with the dominant south lineation produces a checker board appearance on some rock surfaces4 ,a system of east-west trending folds is traced by some of the quartz lenses4 ,the significance of the east-west structures is hypothetical1 but they are believed to have been mostly obscured by the younger structural features4 ,illustration3 ,figure #d4 ,folding and crenulations in the mica-albite-quartz schist near the ,chin on ,mount ,mansfield4 ,as the photograph is looking to the north1 it may be noted that the folds are asymmetrical with axial plane of the folding dipping east4 ,with the description of the rocks completed1 the question which arises next is how to represent these three-dimensional contortions on the map4 ,figure #f illustrates how the attitude of a particular layer may be expressed in terms of dip and strike4 ,it is apparent that the dip of the rock layer may vary from #j to #ij and is measured as the angle between its plane and a horizontal plane4 ,also1 it is apparent that the trend of the bed1 or the strike1 may correspond to any direction of the compass and can be measured as the intersection of that plane and a horizontal plane4 ,the maximum dip is always at right angles to the direction of the strike4 ,illustration3 ,figure #e4 ,diagrammatic three dimensional sketch illustrating the relations between outcrop patterns of folds on vertical planes perpendicular and parallel to the trend of the folding 7front and sides of the block7 and on a horizontal surface 7top of block74 ,cut-away section of the block shows the folds and lineation lines on a given foliation surface4 ,these folds can be more clearly visualized if the upper portion of the diagram is covered4 ,the dip and strike are used to measure the position and attitude of the layers of the rocks4 ,in the case of the mica-albite-quartz schists these planes are called foliation planes4 ,if the structure of the rock is an anticline1 most of the strikes of the foliation are parallel1 but the dips are in different directions on either side of the crest4 ,at the crest of the fold the foliation is horizontal if the fold is not plunging4 ,on ,mount ,mansfield where the plunge is about ten degrees to the south1 foliation along the crest strikes about east-west and dips about #aj south4 ,away from the crest1 the dip of the sides of the anticline begin to be expressed in the readings so that the strike directions 8swing back0 toward the north-south direction4 ,the majority of the layers on the east side of the mountain strike northeast and dip to the east with the angle of dip increasing away from the crest of the anticlinorium4 ,on the west side of the mountain they trend to the northwest and dip to the west with the dips becoming steeper away from the crest4 ,in addition to these variations in the dip and strike over the anticlinal crest1 the smaller folds give local abnormal readings4 ,for these reasons many of the dips and strikes shown on the geologic map represent the averages of a number of readings1 and those of the minor folds and crinkles have been omitted in order to simplify the picture4 ,illustration3 ,figure #f4 ,three dimensional diagrams showing variations in dip and strike4 ,plane in ,a strikes ,n #de ,w and dips #de ,,sw2 ,b strikes north-south and dips #fj east2 and the plane in ,c strikes ,n #de ,e and dips #cj ,,se4 ,another structural feature of the schists is the breakage of the rocks along definite plane surfaces called joints4 ,these usually occur in systems formed by a number of parallel joints4 ,the joints formed as a result of stress and strain operating on the rocks during periods of mountain-making and vertical uplifts4 ,information as to the nature of these forces might be obtained if all the joints were carefully recorded and plotted on a map4 ,on ,mount ,mansfield some of the prominent topographic features appear to be controlled by joints4 ,much of the north-facing cliff on the ,nose is controlled by a joint trending ,n4 #fe ,w41 and a similar face on the ,lower ,lip is controlled by a joint trending ,n4 #fj ,w4 ,along the crest of ,mount ,mansfield a number of joints trend about north-south4 ,joints of this system in the steep cliffs on either side of the crest of ,mount ,mansfield have been separated further by the tendency of the rocks to creep down slope under the force of gravity4 ,these joints form the canyons or narrow passageways which are traversed by some of the trails4 ,on ,maple ,ridge at about #ccjj foot elevation the trail crosses a joint trending ,n4 #ej ,e4 which is conspicuous for its four-foot width and the extent and the straightness of the break4 ,a number of joints belonging to this system are found along ,maple ,ridge4 ,,glacial ,,history ,,of ,,the ,,area ,introduction ,the geologic time division previous to the present one is called the ,pleistocene or the 8ice age40 ,during this time1 large continental glaciers advanced over the northern part of ,north ,america several times4 ,the cause of the ice age is not known with certainty and whether geologic history will repeat itself is a matter of conjecture4 ,however1 it is established that these vast ice sheets covered ,new ,england and that the last ice sheet melted back from the ,mansfield area about #ab1jjj years ago4 ,if one stands on the crest of ,mount ,mansfield and looks westward over the ,champlain ,valley1 it is difficult to visualize this entire valley completely filled with ice of the continental glacier4 ,yet1 the evidence shows that the ice sheet was so thick that it completely covered ,mount ,mansfield at one time4 ,evidences of glaciation ,two types of evidence1 glacial striae and erratics1 show that ,mount ,mansfield was over-ridden by the continental glaciation4 ,striae are scratches in the bedrock which were produced by the sharp edges of rocks protruding from the sole of the moving glacier4 ,these scratches show the direction in which the glacier was moving at a particular spot and the average of many readings gives an accurate value as to the overall direction of movement of the ice sheet4 ,on the ,long ,trail between the ,mount ,mansfield ,hotel and the ,chin on ,mount ,mansfield1 striations may be observed at a number of places4 ,some of the positions where readings were made are indicated on the map by the triangular-pointed arrows4 ,faint striae may be seen near the entrance of the ,mount ,mansfield ,hotel and more conspicuous ones are visible on the west side of the roadbed of the secondary road that intersects the ,toll ,road just below the ,hotel4 ,figure #g shows a photograph taken at ,drift ,rock in which the striae are clearly visible4 ,the average trend of the striae on ,mount ,mansfield is about ,n4 #ej ,w4 ,the movement of the ice is presumed to have been nearly north-south down the ,champlain ,valley which was deepened by the erosive action of the ice4 ,these facts seem to suggest that the movement of ice over ,mount ,mansfield was marginal and nearly #de to the axis of the main ice tongue4 ,erratics are boulders moved and deposited by glaciers4 ,often these boulders are found in environments foreign to them4 ,on the high parts of ,mount ,mansfield1 a few boulders other than the mica-albite-quartz schist are found which have reached their present position by glacial transportation4 ,a particularly interesting erratic is ,drift ,rock4 ,one may note by referring again to ,figure #g that the glacial striae pass beneath the large boulders indicating that the boulders were not at their present position when the striae were formed4 ,thus1 these boulders are aptly named for they must be considered erratics even though their composition is the same as the surrounding rocks4 ,as a logical speculation it is probable that they were plucked out of the bedrock just a short distance to the northwest of their present position and it is possible that these were the very boulders that formed the striae4 ,other evidence of glaciation is the presence of cirques which are the high mountain basins in which mountain glaciers originate4 ,small mountain glaciers probably existed on ,mount ,mansfield1 particularly in the east side of the mountain where the topography has the suggestive form of cirque-like walls and basins4 ,melting of a continental glacier causes deposition of the sand and gravel scooped up and transported by the glacier4 ,some of this material is plastered beneath the moving glacier1 some is simply let down as a blanket and terminal accumulations1 and some is transported by streams of melt water to form deposits in which the sands and gravels are somewhat sorted in size by the action of the water4 ,illustration3 ,figure #g4 ,drift ,rock1 glacial erratics along the ,long ,trail on ,mount ,mansfield4 ,note the glacial striae trending away from the viewer and passing beneath the boulders4 ,the blanket type of glacial deposits probably were present over much of the ,mount ,mansfield area at one time1 but have been removed from the upper mountain slopes by erosion4 ,such deposits are present at lower elevations but are only rarely discernible because of the heavy vegetation and soil cover4 ,sand and gravel deposits derived from post-glacial streams are located in some of the lower valleys as1 for instance1 along the highway north of ,barnes ,camp4 ,north of the old road and northeast of the camping area along one of the main streams on the west side of ,mount ,mansfield1 fine-grained1 sandy lake deposits occur at an elevation of about #aijj feet4 ,the nature of the deposits indicates that they were formed in ponds marginal to the ice sheet when the continental glacier occupied the ,champlain ,valley but did not extend over the crest of ,mount ,mansfield4 ,,descriptions ,,of ,,individual ,,localities ,spruce ,peak and ,sterling ,pond ,spruce ,peak is the mountain on the east side of ,smugglers ,notch4 ,it may be reached by several trails or the ski lift4 ,an excellent view of ,smugglers ,notch and the surrounding country is obtained from the summit4 ,near the summit along the access road to the ski lift1 unweathered mica-albite-quartz schist is exposed and the folding can be clearly seen4 ,sterling ,pond lies to the northeast of ,spruce ,peak in a shallow depression along the divide of the mountain4 ,this location is anomalous for a pond because the amount of higher land around it is so small that only a limited amount of drainage area is available for the accumulation of rain and snow4 ,yet1 the outflow of water is almost continuous during the summer4 ,the basin occupied by the pond was probably scoured out by the glacier4 ,the ,sterling ,pond area contains talc deposits which probably would be commercial if they were not so inaccessible for mining4 ,these deposits have been studied by ,a4 ,h4 ,chidester of the ,united ,states ,geological ,survey and a report is obtainable from the ,u4 ,s4 ,government4 ,the occurrence of the talc1 as mapped by ,chidester1 is shown in the sketch of ,figure #h4 ,talc has the composition of ,mg,si,o7,,oh7 and is a soft flaky white mineral4 ,the talc-bearing rocks in this area are white1 light gray1 or light green and usually are irregularly stained yellow-brown by the weathering of an iron-bearing mineral that occurs with the talc4 ,because of its extremely soft nature1 the talc does not form prominent rock exposures4 ,as shown by the figure1 the talc can be most easily observed along the shore of ,sterling ,pond1 south of the ,green ,mountain ,club cabin1 or along the trail to ,smugglers ,notch near the top of the first rise from the pond4 ,here the talc is exposed in the trail as low1 rounded1 slippery knobs of 8messy looking0 yellow-brown rock4 ,as part of the pond is underlain by talc1 it is probable that the softness of the talc was a factor in the differential erosion of the basin by the continental glacier4 ,the talc is believed to have originated by the alteration of a body of ultramafic igneous rock1 which is characterized by having a low silica content and a high magnesium content4 ,sometime during the mountain-building period1 the ultramafic igneous rock invaded the pre-existing rocks from an unknown source within the earth's crust4 ,it is believed that at a later date the original minerals in the igneous rock were altered to talc and other minerals by the action of hot ascending solutions composed principally of water4 ,illustration3 ,figure #h4 ,sketchmap showing the location of the talc-bearing rocks at ,sterling ,pond4 ,,map ,,of ,,the ,,sterling ,,pond ,,area ,,forest ,,boundary ,green ,mountain ,club cabin ,,sterling ,,pond ,to ,smugglers ,notch ,,explanation ,talc-bearing rock ,solid areas are positions of exposures ,postulated boundary of talc body beneath pond ,trail ,to ,spruce ,peak ,from report by ,a4 ,h4 ,chidester ,the ,long ,trail passes by ,sterling ,pond1 where the ,green ,mountain ,club has erected a small cabin overlooking the pond4 ,figure #i is the picturesque view of ,mount ,mansfield taken from the cabin4 ,smugglers ,notch ,all of the rocks exposed at ,smugglers ,notch 7,figure #aj7 are the mica-albite-quartz schist which locally contains garnet4 ,the large rock boulders in the ,notch were derived from the cliffs forming the walls of the ,notch4 ,the gradual processes of weathering and breaking up by freezing cause large slabs of the rock to become loose and eventually break off the cliff faces to careen down the mountainside to the valley below1 just as ,king ,rock did within historical time4 ,at the north end of the ,notch1 the large accumulations of such boulders form a talus slope1 the name for rock accumulations at the base of a cliff4 ,the irregular stacking of these rocks have formed ,smugglers ,cave4 ,smaller openings extend further back under the 8rock pile0 to where the ground is considerably colder and where the heavier cold air has sunk4 ,drafts of this air escaping at the foot of the talus is noticeably cool4 ,the ,smuggler's ,face1 ,elephants ,head1 the ,singing ,bird1 and the ,hunter and ,his ,dog are freaks of nature and a product of man's imagination4 ,their existence is due to the haphazard nature in which the rocks on the cliff faces have broken along joint surfaces4 ,the origin of the ,notch is not completely known4 ,the steep walls and the narrowness of the ,notch suggest that it could not have been formed by the headward erosion of two streams or by glacial action4 ,it seems most likely that it was formed by the erosive action of an ancient river that once flowed through the area4 ,because of the high elevation1 the only time when such a river could have existed is when the ,champlain ,valley was filled with ice on the west side of ,mount ,mansfield1 so that the normal drainage of water to the west was blocked by the ice4 ,it is possible that the conditions were such that the water supplied by the melting glacier could only drain to the south through the ,notch4 ,after the ice retreated the drainage system was abandoned in favor of lower outlets and eventually the drainage was developed to ,lake ,champlain in the west4 ,the ,notch was modified by the headward erosion of the present small streams4 ,except for the shape of the ,notch1 the only evidence for this hypothesis is the occurrence of a weakly-bedded1 well-sorted deposit of sand at the north end of the ,notch at an elevation of #bjej feet4 ,such a deposit of sand is characteristic of standing water1 which occurring at this elevation indicates that some vastly different drainage system must have existed in the past4 ,illustration3 ,figure #i4 ,the ,chin and ,bear ,head on ,mount ,mansfield viewed from ,sterling ,pond4 ,illustration3 ,figure #aj4 ,view of ,smugglers ,notch and ,spruce ,peak from ski slope on ,mount ,mansfield4 ,big ,spring ,on the south side of the ,smugglers ,notch road at an elevation of about #ahjj feet is the ,big ,spring which furnishes a tremendous output of cold spring water4 ,the source of the water is not known although it is likely that1 like most springs1 it is derived from an underground drainage system4 ,the spring probably originates by the seepage of water derived from the winter snows and rainfall in ,spruce ,mountain through a joint system within the mountain4 ,no buried stream channels could be located between the spring and the base of the massive overhead cliffs4 ,the belief that the spring is related to ,sterling ,pond is unfounded4 ,it is unlikely that surplus water could be drained from ,sterling ,pond because it already maintains a delicate balance between the supply of water from rain and snow and the output to the stream flowing to the north4 ,mount ,mansfield ,the summit of ,mount ,mansfield when viewed from a distance has the resemblance of a face with an exaggerated distance between the nose and upper lips4 ,accordingly1 these peaks are named1 from south to north1 the ,forehead1 ,nose1 ,upper ,lip1 ,lower ,lip1 ,chin1 and ,adam's ,apple4 ,all these points are readily accessible by the ,long ,trail and the area of the ,nose may be reached by the ,toll ,road or the ,ski ,lift4 ,from all the points along the crest an excellent view may be obtained4 ,on clear days ,lake ,champlain and the ,adirondack ,mountains in ,new ,york ,state may be seen to the west1 and ,mount ,washington in ,new ,hampshire may be seen to the east4 ,of the local structures1 good exposures of the mica-albite-quartz schist occur along the crest with magnetite and garnet locally abundant4 ,the rocks on ,sunset ,ridge1 which extends west from the ,chin1 can be seen clearly to be dipping at gentle angles to the west4 ,the ,chin has an elevation of #dcic feet1 which is the highest point in ,vermont4 ,most of the schist in this area is nearly horizontal or dipping slightly to the west4 ,however1 minor folds are present everywhere and an average reading is difficult to obtain4 ,at the summit much of the schist contains large black grains of magnetite4 ,the summit is reached by the ,long ,trail along the crest of the mountain from the ,toll ,road1 by the ,long ,trail from ,barnes ,camp via ,taft ,lodge1 or from the west by the trail up ,sunset ,ridge4 ,an excellent view of the ,lake of the ,clouds and the ,adam's ,apple is obtained a short distance north of the summit of the ,chin4 ,illustration3 ,figure #aa4 8,subway0 formed by separation of the rocks along a joint on west slope of ,mount ,mansfield4 ,lake of the ,clouds which lies north of the ,adam's ,apple and ,bear ,pond which lies north of ,bear ,head ,mountain are both small shallow bodies of water4 ,the slight depressions in which they occur were probably scooped out by the erosive action of the glacier4 ,illustration3 ,figure #ab4 ,cave of the ,winds4 ,mount ,mansfield1 as seen from the east slope of the ,chin4 ,the ,mount ,mansfield ,hotel and the ,nose are in the distance4 ,the rocks in the foreground show the beginning stages of downhill slippage of a large mass of rock away from the joint4 ,between the ,chin and ,mount ,mansfield ,hotel are a number of interesting trails4 ,the ,subway and ,canyon trail on the west side of the mountain follow1 for part of the way1 joints in the rock which have been enlarged by the downhill slippage of the western block4 ,figure #aa shows the nature of one of these passageways4 ,on the east side of the mountain1 the ,cliff trail passes through a similar joint called 8,wall ,street40 ,the ,cave of the ,winds1 reached by a trail just north of the ,lower ,lip1 has formed along another north-south joint4 ,the block which has moved downhill has tilted into the mountain and rubble has filled the gap at the top to form the cave4 ,figure #ab shows the appearance of the cave as seen from the eastern slope of the ,chin4 ,this photograph shows smaller joints on the ,chin which have just begun to be enlarged by slippage of the downhill block4 ,it is possible that some of these open joints date back and partially owe their origin to glacial erosive action4 ,drift ,rock which is located along the ,long ,trail south of the ,upper ,lip has already been described as an erratic boulder moved by the glacier4 ,the glacial striae may be seen in the bedrock northwest of the boulders4 ,garnet crystals are very abundant in these boulders and specimens of the small red garnets may be obtained here4 ,the ,nose is easily reached along the trail from ,mount ,mansfield ,hotel4 ,from the summit the view is excellent to the south towards ,camels ,hump1 which is one of the prominent peaks of the ,green ,mountain range4 ,the mica-albite-quartz schist on top of the ,nose has many small folds and crenulations4 ,south of the ,forehead along the ,long ,trail1 cliffs of an albite-rich variety of the mica-albite-quartz schist form obstacles which have been surmounted cleverly by the ,green ,mountain trail-markers4 ,in the southern part of ,mount ,mansfield ,state ,forest the ,long ,trail passes through ,nebraska ,notch in the vicinity of ,taylor ,lodge4 ,this notch also was formed by the erosive action of an ancient river that flowed across the mountain at this point1 but which has long since been abandoned4 ,illustration3 ,the cliffs at ,smugglers ,notch as seen looking south from the west wall of the ,notch4 ,,footnotes #a,rocks are classified as being either igneous1 sedimentary1 or metamorphic4 ,igneous rocks form by the solidification of molten material2 sedimentary rocks form by the accumulation of sediments derived from older rocks2 and metamorphic rocks form by recrystallization of older rocks under conditions of high temperatures and pressures4 ,illustration3 ,,mount ,,mansfield ,,state ,,forest ,transcriber's ,notes --,silently corrected a few typos4 --,retained publication information from the printed edition3 this e,book is public-domain in the country of publication4 --,in the text versions only1 text in italics is delimited by underscores4