Nada Tunnel EarthCache

NADA TUNNEL

This tunnel itself was built in the early 20th Century, through the solid rock by drilling and blasting. Two teams of workers, one starting on each end used steam hammers and hand drills to complete this project, allowing narrow gage trains to pass through carrying their cargo. Today this pathway is still used as a single lane venue for automobiles from the community of Nada to the Red River Gorge. The tunnel is on the National Register of Historic Places.

BASIC ROCK TYPES

Scientists classify rocks inthree major categories: Igneous, Sedimentary, and Metamorphic.

• Igneous rock are rocks that have been molten under the crust of the earth, have been injected into the layers of the crust and cooled, or have been exposed to the air through a volcano or by volcanic activity, and then cooled. Examples of igneous rock would begranite and obsidian.

• Metamorphic rock is rock that has changed from igneous or sedimentary rock by heat and pressure from underneath the surface. These are usually characterized by a flattened grain structure. Examples of this type would include slate and marble.

• Sedimentary rocks come from rocks that have been eroded or weathered into fine sand-like or clay-like granules, then deposited by wind or water. Over very long periods of time, these sediments are then turned to layers of rock by massive pressures. Fossils are sometimes found in sedimentary rock. Examples of sedimentary rock are limestone, sandstone, and shale.

ROCKS AND MINERALS: WHAT IS THE DIFFERENCE?

Minerals are substances that are the same throughout, in other words they are chemically the same no matter what portion you would test. Rocks are made of two or more different types of minerals combined.

GEOLOGY OF THE AREA

The defining geologic strata of the Red River Gorge were formed about 300 million years ago. Sediment, sand and pebbles eroding from the ancient Appalachian Mountains were carried by a great river and deposited as a delta at the edge of a shallow inland sea that covered much of the middle part of North America at that time. Over millions of years, the mountains were worn down, the sediments turned to rock and the inland sea receded. Gradually, streams began cutting down through the relatively flat layers of sedimentary rock. Because sandstone is a harder rock, it resisted erosion better than the shale and siltstone layers above and below. Erosion and weathering over millions of years sculpted the striking sandstone cliffs and intriguing geologic features that we see today in the Red River Gorge. The deeply dissected landscape is an intricate maze of narrow, winding ridges and valleys separated by steep slopes and continuous bands of high sandstone cliffs, making travel between the uplands and valleys very difficult.

This area is rich in geology with exposed limestone and sandstone, and has an estimated 150 sandstone arches, in fact there are more natural arches here than any other state, except for Arches National Park in Utah. For more information on the park itself please contact:

NATURAL BRIDGE STATE RESORT PARK 2135 Natural Bridge Road, Slade, KY 40376-9999 (606) 663-2214 (800) 325-1710

Questions:

1. From the informational sign near the posted coordinates, what valuable natural resource was this tunnel built to allow easier transport of?

2. What type of rock is in this area: Igneous, Sedimentary, or Metamorphic?

3. Estimate the height of the rock face (from the road to the top of the rock) on the end nearest the coordinates.

Post a picture of you holding your GPSr, with the tunnel in the background. Please remember that you do not need to go in or near the tunnel to log this find. In fact to do so may be dangerous because of traffic entering/exiting the tunnel itself. If you drive through please remember to turn your headlights on to allow others to see you from the opposite end. If you are on a motercycle be aware that on a sunny day your ability to see in the tunnel will be severely restricted untill your eyes become accustomed to the dark. I know.

An easy way to estimate the height of an object is to compare a known height of another object, the tunnel itself for instance (info on the sign). To do this take a stick or similar object, hold it vertically in front of you at arms length. Align the top of the stick with the top of the tunnel. Now grasp the stick in your hand so that your fingernail is at the bottom of the tunnel, this marks the known height, meaning that the distance between your fingernail and the top of the stick represents the height of the object you are measuring. Then simply move the stick up to where your fingernail is now at the top of the tunnel. The height of the cliff at the top of the stick is now 2 times that of the tunnel. Keep doing this until you have the estimate of the entire object to be measured. This works better if you stand back 100 feet or so.

Thanks to Cav Scout for helping us get this EarthCache set up. The resources I have used to get this information include various websites, textbooks, and on-site investigations.