,illustration3 ,cover picture3 ,view of ,burke ,mountain 7center1 background74 ,picture taken toward the northeast from ,state ,route #aad1 about #e miles south of ,east ,burke4 ,,the ,,geology ,,of ,,darling ,,state ,,park ,by ,,harry ,w4 ,,dodge1 ,,jr4 ,,vermont ,,geological ,,survey ,charles ,g4 ,doll1 ,state ,geologist ,,department ,,of ,,forests ,,and ,,parks ,robert ,b4 ,williams1 ,commissioner ,,department ,,of ,,water ,,resources #aifg ,illustration3 ,figure #a4 ,map showing the location of ,burke ,mountain 7,darling ,state ,park71 and mountain peaks which can be seen from the summit of ,burke ,mountain4 ,jay ,peak #ci ,,miles #chfa ,gore ,mtn4 #be ,,miles #cccj ,monadnock ,mtn4 #bi ,,miles #cadj ,haystack ,mtn4 #ce ,,miles #cbbc ,belvidere ,mtn4 #cd ,,miles #ccfj ,willoughby ,lake #ae ,,miles ,bold ,mtn4 #ae ,,miles #ccae ,mount ,mansfield #dd ,,miles #dcic ,stone ,mtn4 #aa ,,miles #bgec ,mount ,washington #ce ,,miles #fbhh ,camels ,hump #ej ,,miles #djhe ,mount ,ascutney #hj ,,miles #cadd ,,the ,,geology ,,of ,,darling ,,state ,,park ,by ,,harry ,w4 ,,dodge1 ,,jr4 ,,introduction ,darling ,state ,park1 located in northeastern ,vermont 7see map1 8,burke ,mountain10 ,fig4 #a71 offers outstanding opportunities to the camper1 picnicker1 hiker1 view-seeker and winter sportsman4 ,on a clear day the top of ,burke ,mountain offers a most spectacular view of northeastern ,vermont and such distant points as ,mount ,ascutney 7located on the ,connecticut ,river1 some #hj miles as the crow flies1 to the south74 ,other prominent peaks that may be seen are ,camels ,hump 7#ej miles southwest71 ,mount ,mansfield 7#dd miles west71 ,jay ,peak 7#ci miles northwest71 and ,mount ,washington 7the highest ,peak in the ,new ,england ,states and the northeast1 which is located in ,new ,hampshire some #dg miles southeast of ,burke ,mountain74 ,for the traveler1 the view from ,burke ,mountain reveals 8where he has been0 and where he might 8next go40 ,see ,figure #a for the location of points which can be seen from the overlooks atop ,burke ,mountain4 ,both the professional and amateur naturalist will find ,darling ,state ,park extremely interesting4 ,this pamphlet is devoted primarily to the geology of the park1 but the fauna and flora of this area present the visitor with days of interesting studies4 ,it is hoped that in the near future pamphlets describing these aspects of ,darling ,state ,park will be published4 ,,the ,,geology ,,of ,,the ,,park ,before discussing the more detailed aspects of the geology of ,darling ,state ,park1 certain basic geologic concepts must be explained4 ,but1 even before such a discussion1 it might be best to clarify the position of geology among the many other1 and oftentimes interrelated1 sciences4 ,the basic reason for the science of geology might be said to be twofold2 one is economic1 the other related to ,man's basic curiosity4 ,in the first1 the geologist through the use of his knowledge of the earth's rocks1 locates those indispensable minerals and fuels without which our advanced society and technology could not exist4 ,in the second1 the geologist tries to unlock the many mysteries within the earth's crust merely to satisfy a thirst for knowledge and to pass such knowledge on to his fellow man4 ,these two basic reasons complement each other and allow continued advancements in geology1 both as a pure science and as a primary economic aid to the nation4 ,as found in most spheres of present-day scientific endeavor1 the geologist relies heavily on other related sciences for insight into problems at hand4 ,a basic knowledge1 and oftentimes an advanced knowledge1 of physics1 chemistry1 mathematics and zoology1 to name only some1 are needed before the geologist can approach many of his own problems4 ,it might be obvious to you by now1 but a geologist will be certainly included in the first scientific party to journey to the moon and planets4 ,within the general science of geology are several branches1 to name only a few2 paleontology1 sedimentology1 mineralogy1 petrology1 stratigraphy1 petroleum geology1 and structural geology4 ,each of these branches or specialty-areas contributes basic data for the overall interpretation of the past geologic history of any given geographic area4 ,the historical geologist takes all these clues and attempts to fit the pieces of information together into a picture of past events4 ,the concept of ,geologic ,time must be understood before the history of ,darling ,state ,park can be unraveled4 ,usually we think of time in terms of minutes1 hours1 days1 weeks1 months and years4 ,the geologist thinks and talks in terms of millions or even billions of years4 ,time units as short as hundreds of years are impossible to distinguish in the past history of the ,earth4 ,when it is realized that the earth is probably #d to #f billion 7#d1jjj to #f1jjj million7 years old1 and the record of these years is incomplete1 it is easy to understand why the geologist speaks in terms of millions of years instead of years4 ,with modern methods of radioactive dating the geologist hopes for finer time definitions in the future4 ,in short then1 the geologist interprets and puts order into millions of years of history which can only be 8read0 as recorded in the rocks beneath our very feet4 ,of course1 just looking at the rocks does not magically open the book of geologic history4 ,this pamphlet is designed to sharpen your powers of observation and to help you in your interpretation of these observations4 ,illustration3 ,figure #b4 ,thin-section of granite from ,burke ,mountain4 ,the main minerals seen in this photograph are feldspar 7light gray center right1 marked with 8,f072 quartz 7whitish1 marked with 8,q072 biotite 7light gray1 speckled appearance1 marked with 8,b074 ,note the interlocking nature of the minerals which make up this rock4 ,magnified #ae times1 under crossed nicols4 ,,the ,,rocks ,,and ,,their ,,history ,the most conspicuous rock found in the park is granite4#a ,along the road which winds to the summit of ,burke ,mountain you will see several outcrops of the white or pinkish biotite granite 7,fig4 #d74 ,this granite is well displayed in the summit parking area and along the trail to the observation tower 7,figs4 #c and #e74 ,a walk down the ,bear ,den ,ski ,trail also shows an abundance of granite outcrops 7,figs4 #f1 #g1 and #h74 ,illustration3 ,figure #c4 ,speckled granite with inclusion of metamorphic rock4 ,black specks in granite are flakes of black biotite mica4 ,metamorphic inclusion1 located just above the hammer head shows some reaction with the invading granite4 ,pieces of metamorphic rock were undermined by and dropped into the granite as it worked its way upward into these rocks4 ,picture taken a few yards west of the tower on top of ,burke ,mt4 ,while looking at some of the above-mentioned photographs1 a second family of rocks is discovered 7,figs4 #c1 #e1 #f1 #g1 and #h2 also1 ,figs4 #i1 #aj1 #aa1 and #af74 ,in many places these rocks have a layered or banded appearance and in other places large lath-like crystals are common in some of the layers4 ,in some areas these rocks are very heterogeneous in appearance and display distorted layers and profuse development of lath-like crystals 7,figs4 #ab and #ac74 ,these rocks belong to the second major family of rocks1 the ,metamorphic rocks4 ,the metamorphic rocks#b seen in the park were originally sedimentary#c rocks4 ,these rocks belong to the ,gile ,mountain ,formation#d which was deposited during the ,devonian ,period some #cjj million years ago 7see ,geologic ,time ,scale#e1 ,fig4 #ad74 ,so much for the two major families of rocks present in the park1 the igneous and metamorphic rocks1 and how to distinguish one from the other4 ,let us assume that you can now distinguish between the granite and the metamorphic rocks4 ,illustration3 ,figure #d4 ,outcrop of biotite granite located on the summit road between the second and third turns from the summit of ,burke ,mountain and on the right side of the road if descending4 ,note the 8sheeting structure0 or flat joint surface which slopes or dips into the road4 ,this flat break in the rock was probably caused by the release in pressure of the overlying glacial ice when it melted from this region4 ,illustration3 ,figure #e4 ,east side of parking area1 summit of ,burke ,mountain4 ,outcrop of granite with many metamorphic rock inclusions 7hammer1 center of picture1 rests on large inclusion74 ,layering or banding in the inclusions is almost vertical4 ,illustration3 ,figure #f4 ,outcrop located about midway down the ,bear ,den ,ski ,trail4 ,alternating metamorphic quartzite and phyllite invaded by lighter colored and speckled biotite granite4 ,note how the granite cross-cuts the layered or banded metamorphic rocks4 ,this cross-cutting points out the fact that the layering or banding was present prior to the invasion of the granite4 ,illustration3 ,figure #g4 ,outcrop located about midway down the ,bear ,den ,ski ,trail4 ,metamorphic quartzite and phyllite 7darker color7 and invading biotite granite 7light speckled appearance74 ,here the granite has a more or less conformable relationship to the layers or bands in the metamorphic rock4 ,compare this relationship with the cross-cutting relationship in ,fig4 #f4 ,for scale1 the handle of the geologic hammer or pick is about #ab inches long4 ,now1 what is the relationship of one to the other8 ,that is1 where you can see both of these rock types exposed together in one outcrop1 can you describe the physical contact of one with the other8 ,for instance1 look at ,figure #f1 which was taken about midway down the ,bear ,den ,trail1 here you see the granite 7the white speckled igneous rock which cuts horizontally across the picture7 cutting across the distinctly layered or banded metamorphic rocks4 ,the granite is said to have a cross-cutting relationship to the metamorphic rocks4 ,in some outcrops the granite is more or less parallel to the layers of metamorphic rock 7,fig4 #g74 ,here1 the granite is said to have a conformable relationship with the metamorphic rocks4 ,still another relationship between the granite and the metamorphic rock is seen in ,figure #h4 ,here1 blocks of metamorphic rocks are inclosed by granite4 ,these inclosed blocks are called inclusions and are pieces of invaded rock which fell into or were encircled by the invading granite4 ,illustration3 ,figure #h4 ,inclusion of layered or banded metamorphic rock 7hammer is resting on this inclusion7 in lighter colored biotite granite as seen along the ,bear ,den ,ski ,trail4 ,the metamorphic rocks were invaded and undermined by the granitic rocks1 with the result that pieces of the metamorphic rock were surrounded by granite4 ,for scale1 the handle of the geologic hammer or pick is about #ab inches long4 ,illustration3 ,figure #i4 ,picture taken along the ,burke ,mountain summit road of typical ,gile ,mountain metamorphic rock4 ,here the rocks dip almost vertically4 ,for those more advanced in geology1 note the pillow-like segments or boudinage structure about one foot to the left of the chisel point of the hammer4 ,this structure is due to a stretching of the rock4 ,for scale1 the hammer handle is about #ab inches long4 ,illustration3 ,figure #aj4 ,banded or layered metamorphic rocks with inter-squeezed granite 7lighter colored material74 ,this outcrop is located on east side of the ,bear ,den ,ski ,trail and quite close to the ,burke ,mountain summit road4 ,the hammer handle1 center of picture1 is about one foot long4 ,illustration3 ,figure #aa4 ,picture taken only a few yards from the ,burke ,mountain observation tower1 along the path to the summit parking lot1 looking northwest4 ,here you see metamorphic rocks 7quartzite and phyllite7 with some inter-squeezed granite4 ,note how the nearly vertical metamorphic rock layers bend or 8wrap-around0 to the right4 ,the highly resistant inter-squeezed granite actually holds ,burke ,mountain up1 or to be more scientific1 it prevents these rocks from being worn down as fast as the surrounding rocks4 ,for scale1 see the clip board in the center of the picture4 ,from these relationships1 what can be said about the relative ages of the two rock types8 ,which is the older1 or first formed8 ,which is the last formed8 ,if you study the above relationships for a minute or so1 it will become obvious that the layered rock had to be formed prior to the emplacement of the granite4 ,some of the minerals now seen in the layered or banded metamorphic rocks were formed at the time of granite intrusion1 but the basic 8stuff0 or partially metamorphosed sedimentary rock was present before the granite entered the area from beneath4 ,so1 the knowledge of the two rock types present and an understanding of their relationship to one another tells us a story of at least two events which occurred in the park area hundreds of millions of years ago4 ,illustration3 ,figure #ab4 ,outcrop on south ,lookout1 summit of ,burke ,mountain4 ,distorted layers of ,gile ,mountain metamorphic rock4 ,lath-like crystals developed along some of these layers during the second period of metamorphism1 that is1 when the granite invaded the metamorphic rocks4 ,for scale1 the hammer handle is about one foot long4 ,can we find other facts in these rocks which might add to the above-mentioned events8 ,the answer to this question is1 yes6 ,the types of minerals found in the metamorphic rocks coupled with the inherited layered structure so common in these rocks1 tells us that they were once sedimentary rocks4 ,there is other evidence which indicates that these sedimentary rocks were slightly metamorphosed and folded prior to the invasion of the granite4 ,added information indicates that these same rocks were subjected to increasing temperatures with the invasion of the granite and another metamorphic mineral change took place4 ,thus far1 the rocks have told us about four distinct events2 the deposition and hardening of the ,gile ,mountain ,formation of sedimentary rocks1 the first period of wide-spread metamorphism1 accompanied by broad folding1 the invasion of the granite1 and a second phase of metamorphism with the increased temperatures produced by this invasion 7see cross-sections illustrating the geologic history of the park area1 ,fig4 #ag74 ,illustration3 ,figure #ac4 ,photograph of the outcrop beneath the observation tower1 summit of ,burke ,mountain4 ,note the heterogeneous appearance of the granite-infiltrated metamorphic rock4 ,here the metamorphic rock approaches granite itself in composition and if the process had progressed a bit more1 it would be said to be granitized rock4 ,large lath-like crystals are very prominent in the rocks of this outcrop4 ,the four events which are mentioned in the preceding paragraph took place hundreds of millions of years ago4 ,what has happened in the park since these events8 ,take a look at ,figure #ae1 which was taken along the road to the summit of ,burke ,mountain 7coming down from the summit1 this outcrop is located on your right1 midway between the second and third turns in the road74 ,here the granite exhibits linear scratches or striations which trend about #dj degrees east of south 7general direction in which the hammer handle points74 ,again1 just down the road from the midway picnic and camping area1 and on your right1 striations can be seen4 ,here they trend about #de degrees east of south or approximately in the same direction as the first series of striations mentioned4 ,these scratches or striations occur in many places throughout the park1 and in most cases their orientation is about the same4 ,what caused these numerous striations8 ,illustration3 ,figure #ad4 ,geologic ,time ,scale4 ,the main ,darling ,state ,park geologic events are noted on the right1 opposite the approximate geologic time when each occurred4 ,,eras ,,periods--,,years ,,ago ,,darling ,,state ,,park ,,events ,,epochs ,,cenozoic ,,cenozoic ,,glacial ,,striations--8,,sheeting ,,structure0 ,pleistocene ,pliocene ,,erosion1 ,,jointing ,miocene ,oligocene ,eocene ,paleocene #gj ,,million ,,mesozoic ,,cretaceous ,,jurassic ,,triassic #bjj ,,million ,,paleozoic ,,permian ,,pennsylvanian ,,mississippian ,,erosion1 ,,jointing ,invasion of ,granite with second stage of metamorphism4 ,,devonian ,regional folding and first episode of metamorphism4 ,,silurian ,deposition of the ,gile ,mountain ,formation4 #cfj ,,million ,,no ,,record ,,in ,,park ,,ordovician ,,cambrian #eej ,,million ,,precambrian ,,time----,,origin ,,of ,,earth1 #d ,,to #e ,,billion ,,years ,,ago4 ,illustration3 ,figure #ae4 ,glacial striations or scratches on outcrop midway between the second and third turns in the road down from the summit area of ,burke ,mountain4 ,striations trend about #dj degrees east of south or in approximately the same direction that the hammer handle is pointing4 ,hammer handle is about one foot long4 ,illustration3 ,figure #af4 ,midway between the second and third turns1 descending on the ,burke ,mountain summit road4 ,metamorphic quartzite and phyllite showing at least two prominent joints4 ,layers are vertical and parallel to the front joint 7one which hammer handle touches74 ,for the more advanced student of geology1 note the lineations parallel to the hammer handle and on the front surface4 ,for scale1 hammer handle is about one foot long4 ,since they are still preserved in the rocks for us to see1 they must have been formed quite recently1 that is1 geologically speaking4 ,what can explain these striations and their common orientation8 ,did you ever hear about the ,great ,ice ,age1 or the ,pleistocene ,epoch8 ,less than one million years ago1 in fact1 some #ab1jjj years ago1 an ice sheet many thousands of feet thick rode over ,burke ,mountain in a southeastward direction4 ,the many boulders frozen to the underside of the ice sheet tended to scratch the rocks over which they rode4 ,the scratches or striations seen in the park rocks were caused by these attached boulders4 ,the ice sheet also plucked and rounded ,burke ,mountain into the shape it possesses today4 ,a look at ,figure #d shows still another event which occurred during recent geological time4 ,the prominent smooth fracture-surface seen to slope or dip toward the road is called 8sheeting structure0 which has its origin in post-glacial time4 ,it is thought by many geologists that these flat surfaces or joints#f1 which are generally parallel to the ground surface1 were formed with the release of the weight of the overlying glacial ice when the glacier retreated northward4 ,so1 here we have evidence displayed in the rocks which tells of still another event in the park's history4 ,it should be mentioned here1 while still on the subject of joints1 that other joints do occur in the park rocks4 ,figure #af shows joints which were formed earlier than the 8sheeting0 and which are not parallel to the surface of the ground4 ,these joints were probably formed as a result of the removal of the overlying rocks through erosion1 thus releasing long-continued pressures produced by the weight of the overlying rocks1 and movement of the earth's crust4 ,we now have the story of two main episodes in the park's geological history2 one took place many millions of years ago1 the other within the last #ab1jjj years4 ,what happened between these two rock-documented episodes8 ,illustration3 ,figure #ag4 ,geologic cross-sections illustrating the geologic history of ,darling ,state park4 7,for explanation of cross-sections see top of page #ai47 #a4 ,deposition and hardening of the ,gile ,mountain ,formation4 ,at this stage the layers of rock were more or less horizontal4 #b4 ,the horizontal and parallel layers of the ,gile ,mountain ,formation were gently and broadly folded and regionally metamorphosed4 ,this is the first stage of metamorphism in the park area4 #c4 ,invasion by granite4 ,this invasion was accompanied by local metamorphism of the invaded rocks4 ,this is the second stage of metamorphism in the park area4 ,note the inclusions of first stage metamorphosed ,gile ,mountain rocks in the granite4 #d4 ,many millions of years of erosion took place1 the forces of nature finally exposing the granitic rocks at the surface of the earth4 #e4 ,continued erosion caused the metamorphically reenforced ,gile ,mountain rocks to wear down more slowly than the surrounding weaker rocks4 ,for this reason1 these strengthened rocks stand higher than the weaker rocks4 #f4 ,less than one million years ago the glaciers advanced over the park area4 ,the glacial ice plucked and scratched 7striated7 the underlying rocks as it slowly advanced southward4 ,during the retreat 7northward7 certain deposits were left4 ,present-day ,burke ,mountain is much the same as it was when the glaciers left1 but1 some added erosion has taken place and1 because of uplift1 the ,mountain stands a bit higher than it did some #aj1jjj years ago4 ,some soil1 much of which was removed by the glaciers1 has since formed on the mountain4 ,there are no rocks present in the park which were deposited during this interval of time1 therefore1 no rock record4 ,if no rocks representing this time interval are present1 one of two reasons must be responsible4 ,either the park area was undergoing active erosion 7wearing down7 during this period1 or sediments were deposited during part or all of this time interval and subsequently completely removed by erosion4 ,most probably1 the intervening time found the park area above the depositional environment of the sea1 when its rocks were being worn away by the erosional forces of nature4 ,again1 see ,figure #ag for a diagrammatic representation of the geologic history of the park4 ,,why ,,is ,,there ,a ,,burke ,,mountain8 ,granite is a very resistant rock1 that is1 it wears away very slowly under the forces of nature4 ,the granite is worn down more slowly than the metamorphic rocks which it has intruded4 ,the granite has been squeezed between and across the layers 7bands7 of the metamorphic rocks 7previously sedimentary rocks7 now found on ,burke ,mountain4 ,in a very true sense1 the granite forms a skeleton framework for the metamorphic rocks of ,burke ,mountain4 ,in other words1 it holds these metamorphic rocks up above the surrounding area of metamorphic rocks4 ,,hikes ,,to ,,take ,a very interesting hike1 both geologically and for nature hunting in general1 is the old fire road which begins just above the old ,c4,c4,c4 camp and the present ,bell ,gardens4 ,this trail cuts off to the right1 if ascending the summit road1 and runs completely around the mountain4 ,shortly after the fire trail intersects the ,bear ,den ,ski ,trail1 and on the left1 granite with obvious drill holes is seen 7,fig4 #ah74 ,most of the granite used as curb stones1 culvert headers1 and islands along the park summit road was obtained from these small quarries4 ,a few miles walk along this trail proves quite rewarding to the adventurer2 an old lean-to demonstrates what a bear can do while sharpening his claws4 ,the ,devil's ,den ,trail leads down the east side of ,burke ,mountain from the observation tower at the summit4 ,this trail is rather poorly marked past a certain point1 but if you wish to strike off on your own and see some wonderful country1 a hike down this trail with a swing to the north will bring you back to the summit road4 ,the several ski trails on ,burke ,mountain are all walkable during the summer1 but they will not appear as smooth as when covered with snow1 and the trip down will take considerably longer on foot than on 8boards40 ,the ,bear ,den ,ski ,trail is especially good for geological sightseeing4 ,,nearby ,,areas ,,to ,,visit ,while at ,darling ,state ,park a visit to ,lake ,willoughby is well worth the trip 7,figs4 #ai1 #bj74 ,a glance at ,figure #a will show you its general location4 ,once you visit this lake1 you might ask 8why so beautiful a ,lake ,willoughby80 ,there is still some question as to the origin of the lake basin1 but a combination of oriented joints and recent glacial movement seems to fit the picture4 ,deeper and faster weathering along parallel joints together with glacial movement and scour in the same direction as the joints probably dug the elongated trench which1 when filled with water1 became ,lake ,willoughby4 ,it is hoped that this pamphlet has given you the desire to enlarge your knowledge of the science of geology4 ,geology is all around you wherever you might travel and a knowledge of geology will open new roads even while traveling old ones4 ,here's luck to you in your travels2 try to see what you look at4 ,illustration3 ,figure #ah4 ,geologic map of ,darling ,state ,park4 ,granite-,metamorphics ,observation ,tower ,burke ,summit ,rd4 ,bear ,den ,trail ,fire ,trail ,park ,boundary ,contour ,line ,dip and ,strike3 ,bed ,dip and ,strike3 ,bed8 ,dip and ,strike3 ,joint ,illustration3 ,figure #ai4 ,view of ,lake ,willoughby1 seen from its north shore4 ,mount ,pisgah on the left1 ,mount ,hor on the right4 ,the ,lake ,willoughby trough was produced by preferential erosion of a joint system accentuated by glacial movement and erosion in the same general direction4 ,the lake bottom opposite ,mount ,pisgah is #baj feet deep4 ,illustration3 ,figure #bj4 ,northwest ,view from the ,burke ,mountain summit road4 ,picture taken just above the old ,c4,c4,c4 ,camp and the present location of the ,bell ,gardens4 ,note ,lake ,willoughby trough in the distance4 ,mount ,pisgah is on the right and ,mount ,hor on the left4 ,lake ,willoughby lies in this trough4 ,,suggested ,,reading ,leet1 ,l4 ,don and ,judson1 ,s41 #aife1 ,physical ,geology1 #crd ,edition1 ,prentice-,hall1 ,inc41 ,englewood ,cliffs1 ,new ,jersey4 ,this is a starter for the geology student4 ,dunbar1 ,c4 ,o41 #aiei1 ,historical ,geology1 ,john ,wiley and ,sons1 ,new ,york4 ,also a beginning book1 read after above book4 ,dennis1 ,john ,g41 #aief1 ,the ,geology of the ,lyndonville ,area1 ,vermont1 ,vermont ,geological ,survey ,bulletin #h4 ,this is for the more advanced student and relates the geology of the area adjacent to ,burke ,mountain and ,darling ,state ,park4 ,jacobs1 ,elbridge ,c41 #aida-db1 ,the ,great ,ice ,age in ,vermont1 ,report of the ,state ,geologist1 ,vol4 #bc2 pp4 #bg-dg4 ,stewart1 ,david ,p41 #aifa1 ,the ,glacial ,geology of ,vermont1 ,vermont ,geological ,survey1 ,bulletin ,no4 #ai4 ,woodland1 ,b4 ,g41 #aifc1 ,a ,petrographic study of ,thermally ,metamorphosed ,pelitic rocks in the ,burke ,area1 ,northeastern ,vermont1 ,american ,journal of ,science1 volume #bfa1 pages #ced-cge4 ,for the advanced student4 ,woodland1 ,b4 ,g41 #aife1 ,the ,geology of the ,burke ,quadrangle1 ,vermont1 ,vermont ,geological ,survey ,bulletin ,no4 #bh4 ,this is a comprehensive study of the ,burke ,mountain area and a must for those interested in ,darling ,state ,park4 ,footnotes #a,the granite found in ,darling ,state ,park is white or pinkish in color and most times is speckled with shiny black mica flakes4 ,on close inspection1 grains of smoky to clear color are seen within the rock4 ,the white and pink grains are the mineral1 feldspar2 the shiny black flakes1 biotite mica2 the smoky to clear grains1 quartz or silica4 ,a magnified picture of a slice of granite 7see ,fig4 #b7 shows the individual mineral grains and their interlocking nature with each other4 ,granite belongs to a major family of rocks1 termed ,igneous rocks4 ,igneous rocks are formed through the hardening or lithification of molten rock-material when subjected to the cooler temperatures at or near the earth's surface4 ,the molten rock material formed at some depth beneath the surface of the earth1 where temperatures were many hundreds of degrees hotter than at the surface4 #b,metamorphic rocks are either sedimentary 7this1 a third major family of rocks which is characterized by a layered appearance that has been retained by many of the altered park rocks7 or igneous rocks 7the granite7 which have been under the influence of pressure1 heat1 and chemically active fluids1 oftentimes resulting in chemical and structural changes4 ,most of the metamorphic rocks seen in the park are either schist1 phyllite1 slate or quartzite4 ,for the benefit of the more advanced student1 the rocks of the park area are considered a granite-hornfels complex 7see ,bertram ,g4 ,woodland's paper of #aifc1 8,a ,petrographic study of ,thermally ,metamorphosed ,pelitic rocks in the ,burke ,area1 ,northeastern ,vermont10 in the ,american ,journal of ,science1 volume #bfa1 pages #ced to #cge74 #c,sedimentary or layered rocks1 the third major rock family1 are composed of pieces1 grains and other materials from older metamorphic1 igneous and sedimentary rocks4 ,these fragments have been carried by rivers and streams to some resting place at the bottom of a sea1 lake1 or stream channel4 ,this mud1 sand and gravel1 under the weight of steadily increasing overburden1 and the presence of cementing materials1 slowly hardened into rock which we now call limestone shale1 sandstone1 and conglomerate4 #d;,a geologic formation consists of a sequence of rock layers which were deposited under essentially the same conditions1 or a series of alternating conditions1 and which can be easily distinguished and mapped as a unit by geologists in the field4 #e;,geologic time is divided into four ,eras which are designated from oldest to youngest3 ,precambrian1 ,paleozoic1 ,mesozoic1 and ,cenozoic4 ,each of these ,eras is divided into geologic periods of time4 ,the ,devonian ,period is in about the middle of the ,paleozoic ,era and began some #ccj million years ago and ended approximately #bij million years ago 7see ,geologic ,time ,scale1 ,fig4 #ad74 #f;,a joint is a break in a rock mass which interrupts its physical continuity4 ,a group of more or less parallel joints is known as a joint set4 ,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