Wisconsin Rocks: A Guide to Geological Sites in the Badger State | Scott Spoolman | KVR

[Music] [Applause] it's a real honor to be invited to speak to your group it's wonderful that your group provides so many services adult and child programming art workshops hands-on community education your lecture series the the Driftless dialogue I'm delighted to be included so thanks again also we we just love to come and wander around the Driftless area which is what we did today and part of yesterday too so good to have an excuse to do that well we're here to talk about my book Wisconsin rocks a guide to geologic sites in the Badger State published by Mountain Press publishers before we get started I do want to take a minute to thank my wife Gayle who's over there and second role I would not be here couldn't be doing this if it wasn't for all the invaluable help Gail's give me its ideas and research coaching and managing so Thank You Gayle well now talk a little bit about excuse me about my book and we'll follow that with some time for questions I can still sign a few copies of the book if you like when it comes to visiting beautiful natural settings such as the Kickapoo Valley what drives me is the desire to understand them to understand how they came to be as beautiful as they are I grew up in northwestern Wisconsin and was was was lucky to have parents who got me into the woods very often to explore now remember one one trip in particular when I was pretty young pretty small we hiked on a trail into the woods south of Ashland and soon started hearing the sound of rushing water as we hike as we hiked along that that sound grew louder and we rounded one bend in the trail and there was beautiful little Morgan Falls this is the first waterfall I ever saw and it was always experiences like this that that sparked my desire to know the stories of such places and Dale and I have carried on the tradition taking our kids well and Katie to explore the places we enjoy since that photo was taken I guess you can see we've all grown some but but it was it was these kinds of experiences that helped to shape my career as a science writer and we're in part that the inspiration for the motivation for my two books Wisconsin State Parks extraordinary stories of geology and natural history published by the Historical Society press and more recently Wisconsin rocks it opens with Wisconsin bedrock map and this can help you to choose a part of the state that you want to visit if you know what sort of features you're looking for such as the courts a outcroppings like the Baraboo Hills or the Blue Hills up north I guess that's where they are or the the long high ridge of dolomite on the eastern side of the state called the Niagara Escarpment or the central sand plain with its beautiful sand stone monuments also being essentially the first page in the book this this is just a very handy handy reference another helpful feature is this is this region's also among the first pages in the book is this region's map it shows you how the sites are distributed among five regions the Lake Superior region northern highlands eastern ridges and lowlands south central and right here in the Driftless area and once you've picked the region you can go to the beginning of that section say the Driftless area and there's a more detailed map there showing exactly where the sites are located and a lot of these most of these section opening pages also have a rock column showing you describing the rock layers that are deep under under the ground another handy reference is this time scale another reference in the introductory section in the first pages is this geologic time Kayle and it includes the different eras periods that make up the Earth's total 4.6 billion year history such as the Precambrian first 4 billion years then the Cambrian a time when the seas that hosted life began to host life and the evolution of life and invaded the area and it includes these important geological events and processes in the Wisconsin region they're keyed to the to the to the timeframe so so following this page is an introductory section which gives gives an overview of the Wisconsin landscapes in geologic history and more detail on those key events and processes in the in the right hand column there for example this section briefly covers the continental collisions that formed ancient North America and built mountains and what would become Wisconsin and its neighboring states several times ancient mountains mountain ranges were heaved up during these mountaineering these continental collisions as depicted here in this diagram near the beginning of the book the introductory section also covers the Mid Continent rift and this was about 1.1 billion years ago when great plume of magma rose from deep in mud in the mantle toward the crust and pried open the long arc in in the crust it's threatened to split the ancient continent in two and the Rift arced through the Lake Superior basin and much of north north north western Wisconsin and it formed it led to the formation of the Lake Superior Basin around the time of the rift excuse me a feature called the Wisconsin dome was being formed now all of north central Wisconsin I highlighted in this this color here this orange or red or whatever that is is slightly elevated or dome-shaped it's probably as a result of the rift and the processes that halted the rift which involves some compression of the Earth's crust led to this mounting up various like this has played a major role in how certain land features have been shaped by erosion in that part of the state the introduction goes on to describe how major faults or cracks caused by earthquakes affected the landscape in some areas these faults created high cliffs as one section of the crust was heaved up against another section of the crust this this waterfall was which we'll revisit in a minute flows over the Douglas Fault in far northwestern Wisconsin and finally this section oh no not finally but this section also describes how invading ancient seas first laid down thick deposits of sandstone later seas hosted a greater and greater variety of life forms whose remains formed limestone on the sea floor which then underwent chemical reactions to be converted to dolomite this is a harder more resistant cousin to limestone layers of sandstone and dolomite eventually covered the whole state totaling thousands of feet thick in some some areas and finally in the introductory section it covers the the quaternary period when the glaciers covered most of Wisconsin but not all of it as we all know for thousands of years slowly shaping much of the state's landscape so now let's go to the geologic sites themselves they're divided among the five regions of the state each of which gets a section in the book and the sites are clearly numbered from 1 to 52 which makes it very easy to find we'll take a quick tour of the regions and we'll in each region we'll explore one site a little more in-depth and then touch on a few of the others just to give you a feel for what the book includes we'll start in the Lake Superior region up here in the far north in Patterson State Park and it's famous for a big Manitou false which you saw a minute ago Wisconsin's highest waterfall fourth highest waterfall east in the eastern half of the country I believe it's our most dramatic display of the Douglas fault the event that occurred about 900 million years ago when the Mid Continent continent rift had been halted in a continental collision to the southeast compressed the crust and the Douglas fault lies on the line along which a massive basalt more than a billion years old was heaped up over much younger sandstone to this to the south of the fault north of the fault sorry the result of this it the result was this escarpment it's 165 feet high at big magnitude Falls downstream from the Falls in Patterson State Park is this beautiful exposure of sandstone from the Precambrian era so this is some of this sandstone is hundreds of millions of years younger than the basalt that's so high above it on the falls this is little manitou Falls also in Patterson by the way how many of you been to paths in state park quite a few so you I'm not telling you anything new during and after the retreat of the glacier the ancient Black River which forms these Falls was a roaring meltwater stream several times during the two and a half million year Ice Age and as these Falls form they formed water falls over weaker Rock and cut notches back into the bus into the escarpment as they as the time went by in this section of the book I also cover an nakhon Falls State Park not far from Patterson another manifestation of the Douglas Fault this photo of big falls in in Annacone Falls state parks show so that Falls is cutting a notch back into the escarpment caused by the Douglas fault and this section of the book also includes the Apostle Islands with their distinctive ancient red sand stones and copper Falls State Park were rivers have been carving up a complex fault zone for 200 million years I also covered Morgan Falls which was the second slide saw tonight in this section of the book so let's move down to the northern highlands the next section in the book and here we'll take a look at site number 12 the rock elm disturbance located about halfway between Eau Claire and the Minnesota border again I'd like to ask does anybody who how many of you know about The Rock Island disturbance Oh quite a few yeah it's relatively unknown feature in our state and for those who you don't know what it is what is the what is the the lark that's the large circle with the small circle inside remind you of your right it's a giant ancient doughnut it's if you're thinking meteor strike that's what it is it's it's it's a it's a meteor crater this is where geologists think that a large meteorite struck the earth four hundred and seventy million years ago this diagram shows three important parts of the feature the rim or the outer perimeter it's about four miles in diameter this inner area called the basin fill and then the central area called the central uplift it's all referred to as the rock elm disturbance named for the little town of Rock Elm in the northern part of the area there now this photo shows normal bedrock in this part of the state flat lying dolomite over older over a young older sandstone much older sandstone however along the outer perimeter of the rock and disturbance the the dolomite bedrock is folded and fractured with chunks of it tilted some of them almost vertical in this in the fault zone of the rim and here's some examples of folded fractured tilted dolomite that a little Creek in nugget lake county park is called blue rock inside the perimeter is more evidence roughly concentric zone of rock types not found anywhere else in this part of the state this is shale here in an old quarry an abandoned quarry north of the county park this area called the basin fill contains a 90-foot thick layer of the shale overlaying by a certain type of sandstone and both of these rock types are estimated to be millions of years younger than the bedrock surrounding them so this means that something strange happened to place these these rocks these rocks here so at and at the center of the circular area is the oval-shaped range of Hills up to a mile and a half across and reaching 200 feet above the surrounding land they're made largely of Cambrian sandstone at least 500 million years old all tilted crazily outward from the center of the uplift and these tilted slabs are thought to have come up from from 800 feet below the surface where this type of stone normally lies in flat layers and I don't have a photo it's on private land so you can't just wander on there however geologists have explored it and one of the things that they also found there was a very dense mineral Rhea dite which is found primarily only at meteor impact sites so there are other theories about what made this strange area up here but but the the meteor strike is really the accepted theory now a passage from my my book describes what geologists think might have been the event that led to all this evidence let's see a shallow sea was still in place when the meteor struck scientists estimate that the meteor estimate the meteor to have been 560 feet in diameter traveling at 67,000 miles per hour when it hit blasting a hole nearly four thousand feet deep and four miles across on a sea floor with the explosive energy of 63,000 Hiroshima sized atomic bombs the blast would have vaporized much of the seawater and flattened everything within 45 miles of the of its center shortly after the collision a slurry of seawater mud and pulverized rock blown up out of the center sloshed back into the crater and the central area of the crater rebounded pulling up rock from deep below to form that central dome and the northern highlands section of the book also includes covers ten other sites including the dowels of st. Croix an interstate park with its famous potholes Willow falls in a state park northeast of Hudson ELLs of the Eau Claire County Park east of Wausau where a rare exposure of ancient volcanic rock called rhyolite was polished for thousands of years by glacial meltwater and the famous waterfalls of Marinette County the far northeastern part of the state where rivers flow over hard ledges created by mountain building process about 1.8 billion years ago so the next section of the book covers the eastern ridges and lowlands so named for its ridges and Lowell hands for example this obviously you know to the door Peninsula is a big high ridge the low land adjacent to it contains Green Bay the Fox River Valley Winnebago and then there's another Highland here in another lowland so it's it's a pattern and for example the site will stop it to explore in depth it's just a few miles south of Green Bay here on the escarpment the Niagara Escarpment and it's called fanfare explan site number 23 a deep narrow canyon cut by baauer Creek which flows over over the escarpment there at that cliff at the head of the Glen the creek for this is the Niagara Escarpment as I said when the streamflow is high makes a really nice waterfall downstream of this cliff in the Glen is this is one of Wisconsin's few stone arches this one being 40 feet high 40 feet high to the bottom there and then five feet thick at the top with a span of 14 feet you can see that the middle section here has been eroded much more than the lower section and the section over it which forms the arch that this middle layer has a different kind of rock that was weakened by seeping groundwater that froze and expanded during winter months over many centuries and baauer Creek did its part to flowing against that that area and roading it away for centuries eventually creating this alcove which kind of collapsed and formed this arch of much harder stone above this section of the book covers ten other sites including Peninsula State Park with its famous dolomite cliffs and wave-cut caves the journey Maribelle caves of north central Manitowoc County created by groundwater dissolving the dolomitic bedrock a whole series of caves here were exposed by streams that gushed through the valley as the glacier was melting away not far from their alleged view nature center near Chilton is a wonderful environmental education facility if you ever get a chance to go to ledge view you should go it's just really a great little place features sinkhole caves and this amazing abandoned quarry that represents many millions of years of deposits of plant and animal remains on that on the on an ancient and that's a sea floor and the Milwaukee Public Museum with its famous displays on geology of Eastern Wisconsin including this life-sized diorama of a coral reef one of the first reefs on the planet according to geologists right here--an was the next section on the book covers the Driftless area but we're gonna save the best for last we're gonna go instead to south-central Wisconsin this section is largely centered on the Baraboo Hills I'm sure most of you or all of you know what that is this canoe shaped outcropping of quartzite covers eleven sites including har fries Glen site number 49 on the South flank of the Baraboo Hills I bet just about everybody in here knows Harvey's going it's one of the many little canyons carved by torrents of meltwater flowing off the retreating glacier and then get and then further by more recent catastrophic floods and it contains loads of evidence of the dramatic geologic processes that occurred here for example on the trail into the Glen you encounter outstanding examples of conglomerate these rounded pieces of quartzite little stones and boulders cemented into sandstone 500 million years ago the Baraboo hills were Islands in the Cambrian sea so this conglomerate serves to indicate that nearby presence of a Sea Cliff a cliff on one of those islands in the sea and the cliff was battered by storm waves that tore loose pieces of rock dropped him into the surf and tumbled him there for decades or centuries rounding them off and then they eventually became cemented into sandstone here's another exposure this was just amazing look at all the layers of conglomerate here in par fries Glen the ancient cliff from which these stones came is still there it lies to the west of the trail into the Glen or behind this wall that you see here it's buried under hundreds of feet of sedimentary rock and soil other signs of the dramatic flooding and carving of the Glen are those gigantic boulders back in the end of the Glen they're near the near the near the head of the Glen these were torn torn by catastrophic floods dropped here by floodwaters another clue is the existence of potholes high up on the wall of the canyon this partial pothole up here is at least ten feet across and as you probably know when ancient streams were roaring through the area they formed Eddie's or whirlpools that would capture olders and rocks and roll them ferociously for decades or centuries until they literally drilled holes into this hard rock look at where it is on the wall way up there and that means that at the time that it was formed the stream bed was up there at that level since then a succession of brutal torrents of floodwater cut this Glen deeper and deeper making it the hauntingly beautiful place that it is today other cutter sites covered in south central Wisconsin include the well-known Wisconsin Dells in the Devils Lake State Park as well as Observatory Hill a mass of ancient volcanic rocks surrounded by much-younger types of sedimentary rock site was often visited by the great Explorer an environmental writer John Muir when he was young the site also includes I mean this section of the book also includes ableman gorge the dramatics exposure of Baraboo quartzite here in an old quarry north of Devil's Lake a great place to hike I highly recommend it if you haven't been there where in that court near that quarry you find Van hise Rock this is an ancient remnant of two distinctly different layers of rock that got mashed together during the formation of the Baraboo Hills and this is where the renowned University of Wisconsin geologist Charles Van hise formulated some principles of structural geology based on what he observed to explain what he observed this section of the book also includes Gibraltar Rock a 300-foot cliff of resistant sandstone in a range of hills across the river let's see I guess that's east of across from Wisconsin River from Merrimack across from Merrimack on Wisconsin River and the UW geology Museum where you can find gorgeous displays of fossils meteorites minerals and the ever-popular Boaz Mastodon found by two young boys as you may know on a farm on their farm back in 1897 it's near oh as I'm sure you know where that is so let's complete our tour of the five regions right here in the ever intriguing Driftless area we'll finish up here in the Kickapoo Valley but to begin let's go a North event to the area of mill bluff in central sand plane much of this area is also Driftless that is never covered by glacial ice although it was certainly affected by the glaciers this photo is taken from from mill up in mill bluff state park where a number of sandstone mounds and buttes and spires have been preserved they were Islands in the vast glacial lake Wisconsin which covered sent the central plain during parts of with the Wisconsin glaciation the most recent glaciation between nineteen thousand and fourteen thousand years ago this map shows the great glacial lake Wisconsin and associated lesser glacial lakes shown in shades of green here the Green Bay lobe of the glacier Green Bay lobe advanced westward from the west toward the end of the Baraboo Hills here the here's the outline of the current Baraboo Hills and this is where the Wisconsin River was flowing back then as well as it is now and the ice climbed up into those hills as you probably know up to got this far before it stopped but it dammed up the Wisconsin River and it backed up into this area of the central sand plain created the Great Lake wasn't it was about as big as Great Salt Lake I understand at that this was a hilly like today's Driftless area and was laced with rivers that were steadily eroding the sandstone that made up those those hills and since then it was but sent but then after the after the glacier moved in it was it was drowned by the by the Great Lake Valley glacial lake and that glacial lake sat there in the deep freeze for three thousand years or so it's waves and currents further eroding the sandstone and eventually leveling the hilly land into a flat lake bed and leaving the more resistant mounds and buttes which stood as islands in those waters and the story of how this lake drained if you haven't heard it is really exciting like all glacial lakes it was held back partly by dams that were made mostly of ice and loose Moreno material and when the climate warmed and the ice began to melt those dams weakened and at some point the key dams holding this lake back which were right there at the Dells and then down here closer to the to the hills to the Baraboo Hills they gave way and the resulting flood was catastrophic a huge torrent of ice water quickly stripped away the bottom lake bottom and glacial sediments and began carving up the underlying sandstone creating today's famous Wisconsin Dells do you all just estimate that within a few days or weeks the main body of the glacial Lake Wisconsin and all the nearby lesser glacial lakes had drained away and here's here's a reading from my state parks book which describes the the aftermath of that flood within a heartbeat of geologic time the vast body of water that had lain for at least 3,000 years in the central part of Wisconsin was gone within a few weeks the famous Gorge of the Wisconsin Dells was created along with the similar dramatic features that we see in some of the areas state parks such as Mirror Lake and rocky Harbor the torrent of ice water icy lake water head hauled gigantic amounts of sand and gravel down into the Wisconsin River Valley and to the northwest lay a vast mucky plain where the lake had been it's rocky islands now standing mute as scattered spires crags and Utes and those scattered buttes and crags once islands in the great glacial lake now graced this central sand plain as a set of features collectively referred to as castellated mounds and that's the name of site number 32 in my Wisconsin rocks book and they include the mounds of these mounds at no Bluff State Park along with Castle Rock near Camp Douglas accessible by a wayside there I'm sure just about all of you probably driven by Castle Rock rocha Cree in a state park 16 miles east of Necedah and it has gorgeous sandstone features like this one stained red by iron oxide and Shiprock at a wayside on highway 21 ten miles east of Rowe Shoukri these and several more such features are made of ancient Cambrian sandstone sculpted by wind flowing water and waves and currents of a lake over many thousand years of course this section of my book covers several sites in the region most people think of when you mention the Driftless area namely thy the hilly area south of the central plain and they include Rock Bridge which is not not far from here a beautiful sandstone ridge at Pier County Park over in Richland County the Vernon County pillars naturally sculpted features of hardened sandstone over near Viroqua that's this one's called monument Rock you've probably seen it and that's my daughter Katie checking it out there Cave of the mounds southeast of Madison with it's bizarre and colorful drip stone features and five state parks including governor dodge State where this photo was taken and that's my son will in that photo there it's a family business that you can see Tower Hill State Park overlooking the lower Wisconsin wyalusing State Park at the confluence of the Wisconsin and Mississippi Rivers borough State Park further up the river up the Mississippi River cross and last but certainly not least Wildcat Mountain State Park lies at the heart of the Driftless area and a river called the Kickapoo runs through it reading from my Wisconsin rocks book sets the stage for the story of the Kickapoo Valley and I think I'm not telling anybody in this room anything new but Kickapoo is Algonquin four he moves about standing now here now they're the Kickapoo River meanders so much that it travels a hundred and twenty-five miles through a drainage basin that is half as long feeding this river are dozens of small tributaries with steep valleys the resulting landscape pattern is called and Riddick which means branching like a tree the deep stream valleys that form the tree branches are called coolies from the French word couleur which means to flow the Kickapoo river valley is classic Coulee country and in in Wildcat Mountain State Park we can travel back and forth in time by hiking hiking around let's begin one one hike on the valley floor starting from the canoe landing and the lower picnic area in the southwest corner Wildcat Mountain State Park at the trailhead for the hemlock Trail my favorite trail there and there at the river level we are among Precambrian rocks they're made of grains of sand carried by rivers to an ocean shore probably well over five hundred and fifty million years ago and at the as that seashore advanced across the land it slowly deposited layers of this sand that later became layers of sedimentary rock the hemlock trail winds its way up a bluff called Mount Pisgah as it veers in and out of the little tributary Cooley's that feed the Kickapoo passing through rare stands of old-growth pine and hemlock and as we climb to the ridge the top on the trail we move forward in time and see younger forms of sandstone deposited by seas that invaded during the Cambrian sometime around or after a 500 million years ago and this sandstone is now displayed in exquisite outcroppings on that hemlock trail intricately carved by flowing water and wind over those millions and as we keep climbing we continue to advance through time and when we get to the top of Mount Pisgah we can see much of Wildcat Mountain State Park and of the Kickapoo River Valley here we are standing on dolomite deposited by at the bottom of another ancient sea that covered the area until about four hundred and forty-four million years ago when it was through so so from the river level to the high point we have crossed through at least a hundred and six million years of time when the last of the ancient seas had departed by about two hundred million years ago dolomite covered all of Wisconsin and layers up up to six hundred feet thick and over the next four hundred million years or so flowing water and wind with the help of winter frost action carved an arterial pattern of streams and rivers and before the glacier arrived much of the Upper Midwest looked a lot like the Driftless area today in this image with the coming of the glaciers most of this ridge and valley pattern was obliterated by the masses of ice and by their by their roaring melt waters over a period of two and a half million years and this is a diagram of the most recent glacier the Wisconsin glaciation but there are several that advanced from the north throughout the Ice Age some geologists think 15 major ice sheets came down during that two and a half million years but the glacial ice was always channeled by lowlands were blocked by Highlands and channeled by other lowlands to the north and the east of the Driftless area and kept avoiding it time and time again and thus the Driftless area is now left as a unique museum piece if you will a preserved sample of what the land looked like before the glaciers arrived from the north the Kickapoo Valley is a well-preserved showcase of Driftless topography that's just part of what makes it such a treasure and I'll leave you with one more reading this one from my state parks book again which also covers what Wildcat Mountain State Park the placid nature of the Kickapoo river belies the fact that it represents an enormous demolition project the dismantling and hauling away of vast volumes of dolomite and sandstone that once made up the mantle covering this part of Wisconsin as you stand near the Kickapoo or if you take it to it in a canoe as many do look up at the bluffs on either side of the valley and realize that all the land in the area was once at that level and higher it took around 400 million years for countless streams to carve an immense arterial system into the ancient bedrock and I can clearly remember the day when I was struck by the enormity of this demolition process that formed the Driftless area as I stood at that canoe landing and looked up gazed along the ridge top across the river there some 350 feet above above the water and that's what inspired the writing and much of the writing that I did in this book about the Driftless area and that's what I hope to share with my readers on my book a sense of the enormity and the complexity of the timeless processes that shape marvelous landscapes such as the Kickapoo River Valley thank you [Applause] [Music] you

Channel: Kickapoo Valley Reserve

Views: 12,858

Keywords: wisconsin geology, scott spoolman, wisconsin rocks, kickapoo valley reserve, driftess dialogue, geology lecture, geologic sites, badger state

Id: SEtMSEVO33Q

Length: 38min 18sec (2298 seconds)

Published: Sat Nov 30 2019