'prophets rock' NATURAL SPRING EC EarthCache
Hidden : 11/20/2010
Difficulty:
2 out of 5
Terrain:
4.5 out of 5

Size: Size: other (other)

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Geocache Description:

As an EarthCache, there is no container to 'find', instead you will discover something interesting about the geology of the area. PLEASE SUBMIT your answers to my e-mail profile. Submit your answers before you submit your find.

REQUIREMENTS:
1- Estimate what you believe the magnitude flow of this natural spring is at the time of your visit. See the classification information (8th--> 1st classifcations)
2- This aquifer IS NOT a large void filled with water. Go to the cave area at N 40 30.268 W 086 51.105 There you will find two large slabs of 'cemented' gravel & pebbles that is a sample of the porous material that this natural spring is filled with. DESCRIBE this porous material---size of pebbles,rocks etc.? Mostly sand or pebbles or rocks or combinations?
3- Based on the "watershed" area above the spring's elevation, and other factors visible from the spring location, what TYPE of spring is this spring likely to be? (Artesian, Seepage, Fracture, Tubular?)
4- Submit a pic of yourself & GPSr at the spring site. OR What is the elevaton difference from the spring site to the bottom of the hill?


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This spring is located near the famous 'prophets rock.' To reach this spring take the steep upward trail that was made by the local Boy Scouts.

One often imagines that springs are "hollow bowls" in the earth, filled only with water with an outlet or spring. In fact, often, these "bowls" are filled with porous "sandstones" and other sedimentary rocks that like a sponge, hold gallons of water, yet fill the space between harder rocks. Conglomerates in this area have often led to this type of springs.

A point of interest is that this spring is located at higher elevation in relationship to the surrounding topography, yet likely is fed by other higher points.

How is that possible? Well, watersheds are the answer. Each body of water, whether the smallest creek, pond, lake, or river is part of at least one watershed. A watershed can be defined as an area in which all water that precipitates to the ground in this region flows towards the same location.

A great way to demonstrate a watershed is to hold your hands in front of you in a cupped position, with the fingers slightly higher than the upraised palms. Then, have someone take a spray bottle of water and spray the fingers (with the crevices between them). Watch as the water collects in the crevices then flows downward into your palms. Think of the crevices in your fingers as streams, and the palms as this spring.

Now, the question is, how is this a spring rather than a pond?

In brief, a spring is "fed" by underground water sources whereas a pond is either fed by a spring or by precipation "above ground" sources. Typically, a pond has no outlet.

How do springs form?
A spring may simply be the result of "karst topography" where water from precipitation has flowed underground and become part of the area's groundwater system. The groundwater travels through a network of cracks and fissures in the underground "caves" and them eventually emerges in a spring.

The forcing of the spring to the surface can be the result of a confined aquifer in which the recharge area of the spring water table rests at a higher elevation than that of the outlet. Spring water forced to the surface by elevated sources are artesian wells.

Non-artesian springs may simply flow from a higher elevation through the earth to a lower elevation and exit in the form of a spring, using the ground like a drainage pipe.

Still other springs are the result of pressure from an underground source in the earth, in the form of volcanic activity. The result can be water at elevated temperature such as a hot spring.
The action of the groundwater continually dissolves permeable bedrock such as limestone and dolomite creating vast cave systems.

Types of spring outlets:
Seepage or filtration spring. The term seep refers to springs with small flow rates in which the source water has filtered into permeable earth.

Fracture springs, discharge from faults, joints, or fissures in the earth, in which springs have followed a natural course of voids or weaknesses in the bedrock.

Tubular springs are essentially water dissolved and created underground channels, basically cave systems.

The amount of water flowing from this spring depends on the amount of rainfall and the size of the underground reservior. Spring discharge is determined by the 'springs' recharge basin. Factors include the size of the area in which the groundwater is captured, the amount of rainfall, the size of the resevior, and the size of the spring outlet.

Flow Magnititude Classification:
Springs are often classified by the volume of water they discharge.

8th Magnitude is less than 1 pint/min
7th Magnitude is 1 pint to 1 gal/min
6th Magnitude is 1 to 10 gal/min
5th Magnitude is 10 to 100 gal/min
4th Magnitude is 100 t0 448 gal/min
3rd Magnitude is 28 to 280 L/s
2nd Magnitude is 280 to 2800 L/s
1st Magnitude is 2800 L/s

In the Central Indiana area, there are several factors that have created a place "friendly" to spring creation. Historically, at least three glacial ages have left a HUGE AMOUNT of glacial geology. Most notably, sandstone and lime have taken the pebbles and boulders left by the earlier glaciers and have cemented them into porous layers of conglomerate rock. The geology of this spring is that a resevior was formed near the top of this hill when glacial meltdwaters deposited a layer of pebbles and gravel when the last glacier receed from this area. This layer of gravel and pebbles were 'cemented' together by lime perculating through it. There is evidence at the nearby cave of this 'cemented' layer of pebbles and gravel.

NOTICE:Greater Lafayette Area Earthcachde Challenge GC2K79J

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