On the rocks local geology is right in front of you special sections ithaca.com what city is the university of kansas in

The word “unique” is generally overused, but the finger lakes region is actually one of a kind. In his 1963 natural history book the finger lakes region: its origin and nature, retired cornell professor O.D. Von engeln described looking throughout the world’s geography for a similar physiographic form and history and he could find none. The lakes were originally river valleys that eroded into what is now the allegheny plateau as it was tectonically uplifted. Then continental ice sheets widened and deepened the valleys, leaving them filled with impressive lakes.

The geology of the ithaca area includes interesting fossils and sedimentary rocks, some unusual igneous intrusions, and a lot of glacial features, both erosive and depositional. University of kansas lawrence ks 66045 in what follows below you will read a brief potted history of the region and be given a short list of places where you can look at the evidence of that history.

You can find fossils in abundance at portland point in lansing, see sedimentary structures in the gorges of taughannock and cascadilla creeks, locate igneous kimberlites in the bed of six mile creek, and see the great sweep of glacial erosion and deposition from the top floor of the johnson museum at cornell.

Fossils are not common in the rocks of the immediate ithaca area because the sediments were deposited into a basin that was too deep to support much life on the bottom and sediment rates were high enough to dilute the remains of organisms amid a proverbial avalanche of mineral matter. As the collision that caused mountain building along the plate margin (roughly just east of the present appalachians) proceeded it actually bent the edge of the plate downward, deepening the continental sea over time.

So as you move north from ithaca the rocks are older, their environment of deposition more shallow, and the number and diversity of fossils greater. In lansing gulf creek has carved down into the middle devonian (397.5 to 385.3 million years ago) rocks that include a lot of fossils, including the tully limestone and the moscow and ludlowville formations. (formations are named for where they were first found well exposed and bundled into “groups”. The moscow and ludlowville formations are in the hamilton group.), which are mostly shale, but include layers of limestone.

The eroded sediments have been carried out to cayuga lake to form portland point, the location of the cargill salt mine. Cayuga crushed stone quarries and owns the land around the creek and permission should be gotten from them before venturing there. You can also sign up for field trips from the museum of the earth at the paleontological research institution, which will get you both permission and instruction about what you find here.

You will find a lot of trilobites, mostly in pieces, but occasionally whole organisms. Also here are several different types of corals, bryozoans, brachiopods, crinoids, nautiloids, and more obscure invertebrates. These are often concentrated in particular beds, as opposed to scattered evenly through the outcrops.

“this layer of rock at the top of the hamilton [group] has somewhere in the neighborhood of 200 different types of critters,” said warren allmon, geology professor at cornell and executive director of the museum of the earth. “in the devonian [period] rocks brachiopods are these most common fossils. You have to actively try not to see them.”

If you don’t want to seek permission or go on a PRI field trip, then you can experience the portland point abundance by visiting the museum of the earth. One of their hands-on stations features piles of portland point rocks to go through. University of kansas fraternities there you have the advantage of having large magnifying glasses to help you identify your finds.

It is an easy walk into taughannock creek gorge; the path is nearly flat and the creek bed itself rests on the tully limestone most of the way to the falls. From the state park parking lot on route 89 you can see a small waterfall created by the tully limestone. This is the same contact you encounter at portland point; the moscow formation is below the fall.

It is actually difficult to get close to the bedrock walls of the gorge because of the large scree piles sloped up against them. It is safer to inspect the large slabs of rock that have fallen into the creek itself. On these large pieces of bedrock you will find ripples, cross-bedding, and abrupt chains in grain size. All of these structures are evidence of changes in the energy of the currents that deposited the sediment in the late devonian (416.0 to 297.5 million years ago).

Three formations are exposed in the gorge wall. At the base is the geneseo formation, which is mostly shale and full of natural gas. Kansas state university tuition fee above it is the sherburne formation, which is largely siltstone. Its thick beds break off in thick blocks. Most of the large slabs in the creek bed come from this formation.

The upper gorge (above and upstream from taughannock falls itself) is cut into the ithaca formation, which is largely shale with subsidiary siltstones. The creek is having a tough time cutting down into the sherburne. Instead the underlying geneseo erodes and the sherburne, undercut, collapses catastrophically at intervals.

Cascadilla gorge is most easily approached from linn street in downtown ithaca near the junction with university avenue. Enter the gorge through the triangle park at the mouth. The footpath has been newly restored up to stewart avenue, but that entrance has not yet been re-opened.

The formation at the top of taughannock gorge is exposed at the bottom of cascadilla. This is the “type section” of the ithaca formation. Formations represent a particular set of environmental conditions that remained relatively stable over time. When the environment changes, a new type of deposition begins, ultimately preserved as a different sort of rock.

The ithaca shales are exposed in the bed of cascadilla creek, so it is easy examine them. You will find very few fossils here, but more of the sedimentary structures visible at taughannock. University of kansas lacrosse in addition, the characteristic “jointing” of the rocks is quite evident here. These sets of vertical fractures occur at right angles to one another and cause the bedrock to erode in a lego fashion. Many first-time visitors are under the impression the outcrops are actually man-made.

The only igneous rocks in the region are kimberlite intrusions that come up through the north-south joints in the upper devonian sedimentary rocks. They date from the late jurassic to early cretaceous period (~145 million years B.P.) and originate in the very top of the mantle. In south africa kimberlites famously include diamonds, but they have a deeper origin. University of kansas buildings our kimberlites are largely composed of the mineral olivine and a type of mica (forming a rock called mica peridotite). They weather to form serpentine.

Because they cut vertical across the sedimentary bedding, these intrusions are called “dikes.” they weather to off-white and gray colors that are usually lighter in color than the surrounding gray shales and siltstones. They also incorporated pieces of the country rock as they surged upward along the joint planes, so there are dark pieces floating in the lighter rock like fruit in a plum pudding.

“as I understand the story, in the 19 th century when geology was getting its act together, people began to look around here for resources and discovered these rocks,” allmon said. “around the same time diamonds were being discovered in southern africa. There was a little boom-let around here, but they never found any diamonds. But there was a suggestion that they should be called ‘ithacites.’”

Six mile creek is an excellent place to see an exposure of these kimberlites, although they can be found in many of the creek valleys in the area. Park at the mulholland wildflower preserve off giles street and follow the trail up the creek for about 15 minutes (~ half a mile) until you reach a site where the pipeline follows a curved retaining wall on the north side of the creek. The intrusions emerge from the creek bank and head toward the creek at an angle. There is a narrower paired intrusion and a wider single one. §