GEOLOGY OF THE RAVEN RUN SANCTUARY completed March, 1985

@over Picture; The stone of Evans' mi11. GEOLOGY OF RAVEN RUN NATURE SANCTUARY Introduction to the trail quide

Geology is the science of Lhe and L11o~:owho study geology are called . Part of a 's job is to determine how the rocks we see today in quarrys, r-oadcuts, parks, and other areas, were ori y inall y formed.

Haven Run Nature Sanctuary is located on Lhe eastern edge of the Bluegrass in cent;ral . This region is a broad, oval that geologists call the Jessamine . The Jessamine Ilorne is part of an even larger feature called the CincinnaLi Arch. Figure 1 shows how millions of ago the in central Kentucky were raised relative Lo I eastern and western Kentucky. The area that was relative1 y uplifted is called an arch. The areas ttml;

PENN. 1. plan. ORD. LATE 220 nllllon vm.18 ago

4 ARCH

END OF PALEOZOIC 100 mllllon v.818 ago

REGIONAL of the CINCINNATI ARCH

CENTlAL IlNTUCIY were relativc?ly downdropped on either side of the arcti are called basins. After the arch was formed re- moved great quantities of rocks and sediments form the arch. This left older rocks exposed on top the arch and younger rocks exposed in the basins. Since Raven Run is located near the top of the arch, some of the oldest ex- posed r-ocks i ri the state are found here.

Most of !;he rocks you can see in the park are call- ed carbonabes. 'rhese types of lacks are predominantly rnatle-up of the calcite. are formed irl warm, shallow seas,often or in part from the remains of small sea creatures. When these remains are preserved Lhey are called . Figure 2 shows how geologists subdivide the carbo- nat,e rocks in the park. The lower and therefore older carbonates are called the High Bridge . The group is divided into three formations. Formations are used to classify rocks that are similar and can be mapped over large areas. At Raven Run, the High Bridge Group consists of Ltie Carnp Nelsorl Limeston Format ion, the Oregon Forma- tion and the Tyrone Formation. The upper and therefore younger carbonates are part of the Lexington 1,imest;one Format ion. The L,exington Limestone Formation can he further subdivided into specific members. Members are sin~plya more detailed c1assifical;ion. Three of the lower members of the Lexington 1,imestone are in Ltlc park. 'T'hese are Ltie Curdsville Member, the Grier Mem- ber and the Tanglewood Member. The members of the Lex- irlg tori I,in~estone Formati on are general 1y buried beneath the on the upper. slopes and'ridgetops of the park. liowevor., the format,ions of the High Bridge Group are s~)ect,acularlyexposed in the gorges and along the trails of Raven Run.. 'I'he rocks that make up these formations were fornted in a shallow sea that covered much of the c?asLerri [Jriited States over 460 million years ago. This Lime was part of what geologisLs call the . Iluri ng the Ordovician period the Raven .Run area probably looked 1 ike the tidal flats and shallow seas of the Bahama Tsl ands today. However, many of the creatures that, lived in this Ordovician sea were very different I HIQH BRlOQE QROUP LEXINQTON LS. 1 rora \,he creatures we see today. Figure 3 is a i llustra- Lion of what the Ordovician seas of the Raven Run area might have looked like 460 million years ago. In those seas were squid-like creatures with shells called ceph- alopods, strange cousins of the horseshoe crab called t,ri lobi tes, creatures that resembled underwater flowers called , prin~itive snai ls called gastropods, prim- itive clam-like called , small - 1 i ke creat:t~rescalled bryozoans, as as many rela- of the modern and marine worms.

F'icjure 4 is a geological map of the park. It js on pnye 6 of' I,his pampl~let. Geological maps are used to show the: formations occuring at the earth's surface. When you start out at the barn, the map indicates that I.l~erocks right below your feet are part of the Lexing- Lon Limestone Formation. When you get down to the water- falls at stop 4 the map indicates that you are standing or1 rocks which are part of the Camp Nelson Formation.

- 'I'hjs pamphlet is a trail guide to the Raven Run Not,ur.e Sanctuary. Points ol- geological interest along Lhe Red Trail are marked on the map (page 6). Brief des- criptions of the points are listed in the following pages 61s geological stops. 'These stops can be seen from the desiynated trai 1s as shown on the map. Walking off the Lrail can be very dangerous and is discouraged. Please do not remove or vandalize the rocks or fossils in the park. 'This park is meant to be enjoyed by everyone. Leave on1 y footprints, take only memories. IN THE ORDOVICIAN SEAS

4 60,000,000 years ago

fig.3 1

1) horn corm1 3) brachlo~ods 5)aloe. 7)marlne worm 8) lrlloblta

2) colonlal coral 4) crlnolds 6) ca~halo~od 8) 0a~lro~od 10) bryoroan of the RAVEN RUN NATURE SANCTUARY CncLTinuM TO?^

flg.4 after Black (1967) STOP 1

As you came down the hillside on the ~edTrail you were walking over the Lexington Limestone Formation. These rocks are called , because they.are pr-e-- dominantly made up of calcium carbonate or "lime". Figure 5 is a sketch of the creek at skop I.;.When you look into Lhe creek . you can seef'tkat. there are many parallel cracks in the limestone..Geo~ogistscall these straight cracks in the roc~~;,~:jo.i.rits~Atthis SLOP the joi.nts are all alligned. in.the. . .. sarne direction. At other. points along the t,F+"iii..yow'may see an additional set of joints alligned:.approx-iinately 80" from this set. Joir~ts can make the rockvery weak, so that it is easily broken apart. As yoi1.walk along the creek you can see how water falls have formed where rocks have broken a.Long the :joir~l:s:

JOINTS BLOCK DIAGRAM of the RAVEN RUN AREA

------A). Park entrance 8). Barn and parklno C). South Fork Raven Run Ck. 0). Mlddle Fork Raven Run Ck. El. North Fork Raven Run Ck. F). Rlver overlook VIEW (3). Chandler Ck. FROM ACROSS THE (ehrt) 'The secontl stop is located 200 feet the trai 1 jurlction. If you look to your right about 20 feet up from Lhe trail you can see a protuding ledge of rock. The ledge is made up of limestone from the Curdsville Member of the Lexing Lor) Leimestone Formation. The 1imestone be- neath the ledge is from the Tyrone 1,imestone Formation. When two formations meet like this, it is called a stra- tigraphic contact. Note the differences between the two types of lime- stone. 'I'he Cur-dsville Limestone is very rough to the touch ;iri$ contains many fossils. The fossils are more easily seen onzthe underside of the ledge. On the other hand, the TyronehLimestone is much snroother to the touch, and (:on tsiris much fefnler fossi1 s. * '-

COMMON FOSSILS

horn corals crinoids bryo roans burrows

Figure 6 shows sonre of the fossils you can see in the ledge rock. These fossils are the remains of creatures that lived here over 460 million years ago. Figure 6 also shows the curious straight lines that you can see in the Tyrone Limestone, beneath the ledge. They represent a different kind of . While the fossils in the ledge represent the actual remains of an , these 1 ines l.epr.esen t the tracks or-ganisms leave behind. They were orlc:e the burrows cjf small worms and clams. When burrows are straight-up 1 ike these, geologists call them 'verti- cal bur~.ows'. They are evidence that creatures were living in the mud on the ancient tidal flats. Apparently when the came iri, the creatures came out of their t)urrows to feed. Then when the tides withdrew, Lhey re- t,r-eated back into their moisL burrows so that they would not dry-01~1, in the hot; sun. STOP 3

Water seeps out of the limestone rocks at sevr-a1 places throughout the park. When these seeps are large enough they are called natural springs. Figure 7 stlows how a may form. falling on the earth's sur- face seeps into the ground. As the '' travcls through the soil it becomes mildly acidic. CarbonaLe rocks, such as limestone can be dissolved underground by these acidic waters. Often the groundwater works i t's way down joints like you saw at stop 1. As the acidic water moves underground it en1 arges the joints, for-ming solutional cavities. Over a long period of , largc amounts of the limestone may be dissolved away, f'orminy a cave. Another feature that may form in this situation are bowl-shaped depressions called . All of these features; the seeps, springs, sinkholes, solution cavities, and caves are called 'karst' by geologists. They are common throughout Ken Lucky. In fact, Kentucky is one of the most famous karst areas in the .

rock debrla

SEEP

NATURAL

uCREEK KARST FEATURES There are many things to see in this area. The rocks at the waterfalls are part of the Camp Nelson Ii'ocn~atiort. 'I'his is the oldest formatior> in the park. I t is also the oldest exposed formatiorl in Kentucky.

if you look at the rocks around the falls or the large near the old mil 1 you can see all sorts of twist-inq fent,l~resChat st;and out; on their surfaces. (:eologi sts believe t,ttese are anot;her kind of fossi1 bur- row. il'i qt1r.c H shows the dif f'erence between these burrows and the burrows that can be seen in the Tyrone Formation. 'I'hese fossi 1 tracks were formed by worm-1 ike organisms niovirrg over or through ttre muds. They are known as hori- zorrl;nl or lateral burrows.

TRACE FOSSILS

then \) -.

then now now vertlcal burrows ('l'yt-one F'm. ) lateral burrows (Camp Nelson Fni. ) S1'0I' 5

A trail loads up the creek to a very large waterfall. It is much safer to stay along the creek and not climb the hillside. Figure 9 gives some idea how the waterfall was forn~ed. The top of the waterfall is a stratigraphic conLacL between rocks of the Tyrone and Oregon Formations. ,Joints, like those you saw at stop 1, created lines of weakness in the rocks. Since, at this location, the - gon rocks were weaker than tire overlying Tyrone rocks, the l'yr-one was left as a resistant ledge for the water to fa 1 l over. But even the Tyrone x-ocks are gradun l 1 y Waler beglns lo erode along lolnl

neslslant rock Iormo a ledge Through Ilme the falls r.etreal up on reslstanl rocks the valley are eroded

Eroded malerlal Is seslrtsnl washed downstream

eroded. Through time the water has eroded the canyon further back into the hillside, to the point where you see it today. Someday, thousatlds of years from now, the falls will retreat even further up the valley.

STOP 6

If you look at the map you can notice that the trail around a small valley that br-eaks away from the main gorge. This valley fol.lows a large break in I,hc: surface of the earth, known as a . Faults differ- from joints because rocks along a fault move. This type of ~rtovement is what causes an . Don't worry the fault you are walking along has not moved for mill- ions of years. Because of all the vegetation and soil cover, the fault is difficult to see. However, many faults can be seen in the roadcuts in the Raven Run area. After leaving the park if you drive over the Kentucky River by Clays Ferry on Old Richmond (Route 25), I or at the bridge near Camp Nelson, on Nicholasville Road I (Route 27) you can see good examples of faults in the roadcuts . 1 i I I The rock at the top of the overlook belongs to the Camp Nelson Formation. This is Lhe same formation you saw back at stop 4. Notice that you can still see the trace fossils in the limestone rocks at your feet. Figure 10 shows a pitcur-e of these burrows and the other comnron Fossils at the overlook.

COMMON FOSSILS at .the overlook

.'-' ......

(3astropoda fanoleni ~naita) Cephalopods Trace FossltS fanotant oqold.) tanai.oI IraaLa f ig. 10 and brrrorl)

Wrtl k out to khe over-look. The center of this pam- phlet has a block diagram thaL shows Raven Run park as it would be seen from across the river. It also shows t-he rock units that are found in the park. In many areas of the Bluegrass, the Kentucky River winds through a gentle valley. But here the river has been forced to through the resistant carbonates of (,he iiigtj Bridge Group. Because they are hard to erode Ltte Kentucky River has had to cut a steep-sided gorge into the rocks, known as the Palisades. Sometimes if you look at the river right below the look-out; you can see a bar. Sand bars commonly form in river bends and at locations where another creek or river join. This sand bar is a result of that has been washed out of the Raven Run gorge. Utimately t,hese sediments, which have been formed by erosion of the rocks in the area, may end up in the Ohio River. From there it may be washed into the Nississjppi River and as far as the Gulf of Mexico, over 1500 miles away! STOP 8 As you head up the from the overlook you will walk through a moss-covered pass. When the trail levels out on the other side of the pass, you are back into the Tyrone Formation. The Tyrone F'ormat;iot~ is easi 1y recog- nized because of it's white color. Most of the other for- mations in the park are dark grey, tan or buff c:olor. Look For the circular mound shapes in the light colored rocks along this part of the trail. These are yet another kind of fossil. Figure 11 shows a sketch of these mounds. They represent the remains of a colonial coral called Tetradium. These corals flourished in parts of the ancient tidal flat, when the Tyrone Formation was deposi Led. You can also see pat,tctr-ns of cracks in Ltle 1 imestonr:. These are called mudcracks. A sketch of these js also shown in figure 11. The mudcracks were formed just as they are today. In some areas when the withdrew, t,he beach area was left to dry in the sun and the muds crack- ed.

COLONIAL CORAL FOSSIL. .

STOP 9

The 1.1lins of the structure in fr-ont of you is a lintestone kiln. A kiln is like a large furnace. Years ago the settlers irl this area baked the limestone, rocks in this kiln to produce 'lime'. The lime was used in making mortar and plaster for construction pur-poses. These types of kilns are no longer important since I i there are now more modern nrethotls for obtairliny 1 i rne. l'he last part of the trail follows the old stone fence. Early settlers commonly used the carbonate rocks of the area for- building. They made good building nlater- ial hecause they broke along joints and bedding planes into block-like shapes. They also ware abundanl; and easily accessibie. The kiln at stop 9 was made out of 1 inrestone from the Lexington L,i mestone Formation. 'The nti l 1 at stop 4 was made out of d~lomiticliniestone from Ltte Oregon Formation. In fact, even many of the more ~rrotfer-n buildings in the towns around the park were made L't.orn t;he carboriate r.ocks Like yo11 saw in the park today. .

'i'his trail quide.was meant to give the visitor to Haven Run a brief introduction t,o the geology of the ULnegr.ass area. If you are interested in learning more about the .ucky many local libraries will be able to help you. Information may also be obtained f rorn the state ilniversi t ies and the Kentucky Geological s1;tl'vey. The +olPowing references discuss in more detail the geology of the Raven Run area.

Black, D. F. B. , Cressman, E. R. , and MacQuown, W. C. Jr. , ( 1965) , "The Lexington Limestone (Middle Ordovician) OF Central Kentucky"; U.S. Geol. Surv., Hulletin 1224-C, Z9pp.

Black, D.F.B., 1967, "Geologic map of the Coletown Quadrangle, east-central Kentucky"; U.S. Geol. Surv. , 6Q-644.

Cressman, E.R., and Noger, M.C., 1976, "Tidal-f lat environments in the High Bridge Group (Middle Ordovician) of Central Kentucky"; U.S. Geol. Surv., Series 10, Report of Investigations 16, 15pp.

Cressman, E.R., 1973, " and depositionak environments of tho Lexington Limestone (Ordovician) of central Kentucky; U.S. Geol. Surv., Prof+essionaI Paper 768, bipp.

MrFarlan, Arthur C., 1943, l+ology of Kentucky; University of Kentucky, Lexington, KY, 531pp.

Topographic Map of the Raven Run Nature Sanctuary, Fayette County, Kentucky; scale 1"=400'.