Under The Sinkhole Plain… Binkley Cave

The Binkley Cave System in Corydon, IN measures in at over 44 miles long currently thanks to the efforts of various survey groups over the years. The Historic Entrance to the cave first made its appearance in the 1920s, when hunters spotted a pit opening up in a large sinkhole where a pond had once been. Initial exploration of Binkley Cave began in the 1930s by Lewis “Lewie” Lamon and cohorts, a group local to the area, referred to as ‘the fathers of caving’ in Southern Indiana.. In the 1950s-1960s, primary exploration was conducted by members of the Bloomington Indiana and Central Indiana grottos, mapping out a 5 mile circle route through the river passages in the cave. In the 1960s, Gary Roberson and crew took interest (from stories they had heard from Lewie at his local hardware store) and began diligently surveying all of the virgin passage they could find!

A special thanks to Laura Demarest… for not only putting this trip together, leading it , but also in providing this content and sharing her knowledge and experiences.

Binkley exploration slowed after the cave reached approximately 20 miles. In 2009, Gary asked Indiana project caver, Dave Everton, to capture photographs for his upcoming book, “50 Years Under the Sinkhole Plain”. While on the job, Dave was intrigued by the potential of the cave and reinvigorated survey efforts. From 2009-present day, over 20 miles has been added to the system, making it the longest cave in Indiana and currently the 7th longest in the USA. Over the years, numerous studies have been conducted in addition to passage survey, including biological assays, dye traces, and stream flow analysis.

Indiana Caverns

Pictured below are photos from the commercial development of one portion of the Binkley Cave system. Indiana Caverns is centralized around a large chamber in the cave called ‘Big Bone Mountain’. It was discovered in 2011 and noteworthy not just for its size and eye-catching composition, but that it contained numerous animal remains dating back to the last ice age. Gary Roberson and business partners purchased the land above, drilled an entrance, and initiated the process of making it tour-ready. Commercialization happened quickly and the cave was open for business by June 2013. Gary was able to realize a lifelong dream of giving tours in his beloved cave system; he wrote another book entitled “The Longest Year” that describes the process of commercializing a wild cave.

Making Our Way Under The Sinkhole Plain

On July 28th, 2018, a group of 10 arrived at the Historic Main Entrance for a sightseeing trip underground in Binkley Cave. Past turkey barns and into a cow pasture, the cavers corralled their cars and started to prepare their gear. Present for this trip were the following fine folks: Ray Maslak and Kevin McGinnis along with their sons, Nick Anderson, Rachel Davison, Katie Elder, Matt Pelsor, Noboru Sakabe, and Laura Demarest.

Of note, Matt Pelsor is the Chairman of the Central Indiana Grotto and host of The Caving Podcast, which did an episode with Laura Demarest previously. To hear the episode, listen below or with iTunes or Google Podcasts.

Back to the trip in late July

The Historic Main Entrance of Binkley, while very scenic, requires much care and attention while traversing down to the stream level. Massive amounts of air moving in/out of a 44 mile cave system increase the amount of freeze/thaw fracture around the entrance, making the risk of rock fall more inherent.

The group descended approximately 200′ from the parking area before reaching the muddy stream that characterizes this cave system. Binkley is often regarded as being one of the most challenging cave systems in Indiana, mostly owing to its ‘sleazy’ mud, long crawlways, wet passages, and long distances to survey frontiers. It is not famous for its speleothems, though there are places throughout the system that are quite remarkably decorated. However, it contains a number of awe-inspiring features, including large river borehole, huge rooms, and the potential for more cave to be discovered. Based on dye trace studies in 2014, it is estimated that the entire system could be mapped to over 100 miles long in the future – exciting prospects that keep project cavers awake at night dreaming!

Above: Lamon’s Cut-Off (aka Howe’s Crossover) is a series of muddy and wet crawls leading to other significant portions of the cave. The early BIG explorers (led by Dave Howe) mapped a 4+ mile loop in the main cave system and this is an important entrance/exit to that loop. Stories from earlier exploration by Lewie Lamon and crew highlight this passage with an exciting story involving the group being very far downstream and running out of carbide. Apparently Lewie suggested they take an unknown short-cut back to the entrance as he had a good feeling that it would connect back into the main stream passage. Miraculously – they were correct, though this route is much more physically challenging, though shorter in distance from the area they were exploring.

Smiling faces during a short break indicate a good trip! A total of 5 hours was spent underground, traversing through the main stream passage and up, over, around, under lots of breakdown. Crawling was minimal on this day as most of the trip was spent casually walking through the stream.

Below: Traversing through ‘The Big Break’ – a series of breakdown climbs/crawls that lead up to the Mountain Room. Route-finding can be challenging as the way through is somewhat of an ‘optical illusion’ in places, making it hard to determine how to proceed.

The Mountain Room (illuminated beautifully thanks to the Acebeam X45!) – a mainstay on the historic Binkley river route. At the back of the room is an alcove that leads to an area called ‘Sandy Road’ where early ISS (Gary Roberson and crew) explorers made camp so they could extend their survey trips over long weekends. The remains of the camp have been left behind for nostalgia purposes and are the source of some light debate as to whether or not the items are of historic value or warrant some tidying up.

The ‘sketchy’ ladder leading up into the Sandy Road camp area. All members of this trip bravely took the challenge. A handline at the top makes getting on and off the ladder much easier than it first appears.

Dome complex in the back of Sandy Road. Early ISS explorers used these sources of water to refill their carbide lamps. The trunk passages continues, but eventually pinches down to a dead end. The Sandy Road area is one the few places in the system that is safe from flooding and remains ‘high and dry’ even in extreme weather events.

Continuing downstream, beyond the Mountain Room, the stream passage changes character significantly, exhibiting less mud and more clean-washed rock. The sediment has been mostly collected upstream of the large breakdown room, leaving this area much more mud-free – a sort of anomaly compared to most of the cave system!

A large population of sculpins inhabit the pools in this area, dragging tracks through the sediment as they feed on detritus. Monster-sized crayfish from the surface can also be found in addition to their obligate cave-dwelling relatives, the blind crayfish. Blind cavefish can also be found in the Binkley Cave system.

Numerous fossil clusters can be found embedded in the limestone ceilings. Brachiopods, crinoids, horn and fan coral, as well as sea urchins in some parts of the cave system.

Heard over and over again from annoying tour lady “DON’T TOUCH THE CEILING”  – the 11th Commandment in Binkley – ha!

Overall, it was a wonderful day under the sinkhole plain (as we like to say in most of our trip reports) – it was my pleasure to take this group and show them parts of the cave I love. Everyone seemed to have a great time getting to know each other underground. With the exception of myself and Nick, all participants were first-timers in Binkley. – Laura Demarest

Please note that caving can be a dangerous activity for the inexperienced. If you have an interest in exploring caves, check out a local grotto from the National Speleological Society website so you can connect with experienced cavers in your area who will show you the ropes. Also, remember that caves can be on either private property or government land so please always ensure that you either have permission from the landowner or the proper permits obtained before visiting a cave. While there, remember to…

Take nothing but pictures.

Leave nothing but footprints.

Kill nothing but time.

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