Lake Rose Sinkhole EarthCache EarthCache
Lake Rose Sinkhole EarthCache
-
Difficulty:
-
-
Terrain:
-
Size: 
(other)
Please note Use of geocaching.com services is subject to the terms and conditions
in our disclaimer.
Welcome to Lake Rose, the site of the Great Winter Park Sinkhole of 1981 which made national news. This earthcache explores the reasons behind this geological and historical phenomenon.
The Great Winter Park Sinkhole of 1981
What happened here?
The ground began to collapse on May 8, 1981 during a time of record-low aquifer levels in Central Florida; by the following day, the sinkhole had expanded to 320 feet wide and 90 feet deep, completely swallowing a two-story home, a long stretch of Comstock Avenue and chewing up pieces of nearby Denning Drive, several businesses, a public swimming pool, and six vehicles (three of which were brand new Porsches at the import car dealership, which was destroyed). Ironically, there was a short-term economic benefit, as the attention of national news outlets led to a carnival-like atmosphere in Winter Park for quite some time; even today one may see locals sporting Great Winter Park Sinkhole t-shirts.
Engineers working for the City of Winter Park eventually stabilized and sealed the sinkhole, turning it into the peaceful urban lake you see today, named Lake Rose after May Rose Owens, the lady whose house was at ground zero and was completely swallowed by the sinkhole, but survived to tell the tale.
What is a sinkhole and what causes one?
Sinkholes are natural depressions in the Earth's surface caused by the dissolution of bedrock, typically limestone or dolomite, though they do occur in some cases in sandstone or other rock formations. They may be as small as a pothole-sized bowl, or form massive, deep caves, and may be formed gradually or suddenly. The dissolution of bedrock may occur over a long period time underground, but be imperceptible on the surface due to the pressure of groundwater maintaining the subsurface layer's ability to support the overlying land.
Sudden, catastrophic collapses of subsurface cavities are commonly triggered by declines in the level of groundwater aquifers or by increased movement in groundwater flow, both of which may easily be affected by pumping; these tend to occur in carbonate rocks (limestone and dolomite) or evaporites (salt, gypsum, and anhydrite). Due to the high solubility of evaporites, sinkholes in those materials form very quickly (days to years), but the formation of cavities in carbonates may take much longer (millennia); activities such as pumping therefore may decrease bedrock stability and induce a massive collapse, as seen here. The effects of a sinkhole extend beyond physical hazards to homes, roadways, and human life; untreated sinkholes in urban areas pose a threat to the aquifer by means of surface contaminants draining underground. It is therefore important for engineers to stabilize sinkholes by sealing those that form in populated areas using techniques such as grouting, as well as limiting erosional effects along the edges of the sinkhole with with riprap, concrete, or vegetation, so as not to affect nearby residences and businesses.
Not all sinkholes are manmade, though: in fact, sinkholes are one of the predominant natural landforms in Florida; if you look at any map of Central Florida, you will see circular lakes, many of which are relic sinkholes that collapsed long ago and have filled with surface water.
It is not necessary (or remotely recommended) to go to the exact coordinates, which are smack dab in the middle of Lake Rose! So long as you are able to fulfill the logging requirements listed below, you are welcome to log your smiley.
To log this EarthCache, please follow the following steps and send the answers by email:
1. Estimate the height difference between the lip of the sinkhole and the surface of the water.
2. Estimate the current maximum width of the sinkhole from lip to lip as it stands today. (You may use a mapping tool if you wish.)
3. Based on what you see here and what you know about sinkholes, what type of bedrock layer lies under here?
4. What is being used to limit or halt erosion along the sides of Lake Rose? Do you see any evidence of further erosion or subsidence?
5. What specific activity caused the Great Winter Park Sinkhole of 1981?
Please do not put answers in your log. Answers that do not meet the above requirements may be challenged and/or deleted.
As per EarthCache guidelines, photos are not necessary, but they are of course highly encouraged. Extra points if you are wearing one of the t-shirts mentioned above!
Until 2014, there was also a physical cache located here, one of the largest I've encountered to date. The logs are here: The Great Winter Park Sinkhole of 1981. I do not recommending looking for it; it may very well itself have become a much more recent victim of the sinkhole.
Sources and Further Reading:
US Geological Survey: Land Subsidence in the United States
http://water.usgs.gov/ogw/pubs/fs00165/
Southwest Florida Water Management District: Sinkholes
http://www.swfwmd.state.fl.us/hydrology/sinkholes/
Orlando Sentinel 25 Nov 1987: "Winter Park's Sinkhole Lake Becomes Rose's Namesake"
http://articles.orlandosentinel.com/1987-11-25/news/0160250270_1_sinkhole-owens-moved-lake-rose
Orlando Sentinel: Winter Park Sinkhole (1981) (archives)
http://www.orlandosentinel.com/topic/disasters-accidents/winter-park-sinkhole-(1981)-EVHST000086.topic
Congrats to celebrationkim for the FTF!!!
This cache has been brought to you by
Clan Miwa
成功は希望を養う。
Cache visitors (as of 5 Apr 2016):
244
159
7
6
5
5
5
5
5
4
4
4
4
4
3
3
3
2
2
2
2
1
1
1
1
1
1
1
1
1
1
14
8
2
1
1
1
11
10
2
2
2
1
1
1
1
1
3
2
1
2
2
1
1
1
1
1
1
Additional Hints
(Decrypt)
Bapr zber sbe cncreyrff pnpuref:
Gb ybt guvf RneguPnpur, cyrnfr sbyybj gur sbyybjvat fgrcf:
1. Rfgvzngr gur urvtug qvssrerapr orgjrra gur yvc bs gur fvaxubyr naq gur fhesnpr bs gur jngre.
2. Rfgvzngr gur pheerag znkvzhz jvqgu bs gur fvaxubyr sebz yvc gb yvc nf vg fgnaqf gbqnl. (Lbh znl hfr n znccvat gbby vs lbh jvfu.)
3. Onfrq ba jung lbh frr urer naq jung lbh xabj nobhg fvaxubyrf, jung glcr bs orqebpx ynlre yvrf haqre urer?
4. Jung vf orvat hfrq gb yvzvg be unyg rebfvba nybat gur fvqrf bs Ynxr Ebfr?
5. Jung fcrpvsvp npgvivgl pnhfrq gur Terng Jvagre Cnex Fvaxubyr bs 1981?