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Lime Kiln Point Quarry and Kilns

A cache by Kiwibirdman adopted by las3dogs Send Message to Owner Message this owner
Hidden : 02/27/2011
2 out of 5
3 out of 5

Size: Size:   other (other)

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Geocache Description:

The listed co-ordinates will bring you to two lime kilns (ovens)adjacent to Lime Kiln Point State Park. This massive mining operation lasted over 80 years and saw the whole hillside clear-cut and gouged out by the quarry. The area has since recovered.

This cache has been placed here with permission of the San Juan Land Bank and the above co-ordinates are on their land.

They were super helpful and excited about having an Earthcache approved on their property.

Please do not climb on or vandalize the kilns or I will be asked to archive this cache

There is no physical box to be found at this site.

What is Lime?

Lime (Calcium Carbonate) comes from Limestone, a sedimentary rock found all over the world. Limestone is formed by the compression of marine invertebrate skeletons over many years.


At this site, the mined calcium carbonate was heated to immense temperatures inside these ovens in order to make the material shed carbon dioxide and gain oxygen in order to transform it into calcium oxide through a process called calcination. The limestone mined here was one of the purest in the world at 98 percent, with the remaining two percent being iron, silica, alumina, phosphorus.

In the beginning, the limestone was quarried with pick axes and sledgehammers but as the operation grew, explosives were later used. The mine carts were filled and then lowered on tracks to the lime kilns below.

Creation of Calcium Oxide

Loads of limestone would be dumped into the top of the kiln and the inner chamber would be heated to 2,000 F (1,100 C) by wood fires. The fires would use about 3.5 cords of wood per day and out of the amount of limestone dumped into the kiln, 45% would be produced in the end. When the lime cooled, it was inspected and any defective portions would be dumped into the sea. Not great for the environment, but it was a different time.


Lime was a dangerous material to ship. When introduced to water, it can heat up to 150 degrees Celsius and ignite anything nearby. Bear in mind that ships were wooden back then. During the mining operation, 200 pound barrels were either loaded onto carts bound for Friday Harbour or loaded onto a ship via a dock which once stood here. The lime would be sent to destinations such as Victoria, Vancouver, Seattle, Portland or even San Francisco or Hawaii! Unfortunately, although the quarry was rich in high quality material, the shoreline was unprotected and storms could make it treacherous for ships. It 1876, the San Juan Company’s schooner Ontario was sunk by a storm.

To Log This Cache

In order to prove that you visited this site and learned something, you will have to send me the answers to the following questions through my account.

1.)Look on the interpretive sign at the restored kiln. When was this restored lime kiln built?

2.) Look at the stains on the rocks were poor quality material was discarded. What colors are these stains?

3.) Just up the hill you should find the quarry quite easily. Find a piece of limestone if you can according to the above description. How would you describe its attributes?

a.) Will it scratch glass? (Hardness)   

b.) Grain size

c.) Luster

4.)    Internet/Library Question: Is limestone a clastic, biogenic or evaportic sedimentary rock?

5.) Optional: Find a nice spot near one of the kilns and take a picture with your party and GPSr.

Note that it does fizz with acid but it’s a potentially dangerous test in the field, especially if you have kids with you.


Additional Hints (Decrypt)

Lbh pna frr gur xvyaf ba Tbbtyr Rnegu.

Decryption Key


(letter above equals below, and vice versa)