Journey inside Colossal Cave Mountain Park – Arizona’s dormant cave

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Before entering Colossal Cave it was essential to educate ourselves and obtain some cave basics.  The facts and information we learned about limestone caves made our trip profoundly interesting!

Colossal Cave is an archaic KARST CAVE (meaning erosion has produced fissures, sinkholes, caverns and underground streams).

Colossal Cave is a Karst cave
Karst region

Karst caves have 3 categories:  limestone, gypsum and quartzite.

Colossal Cave is limestone and considered dormant, “dry”.  A dry cave is without drips of water, streams or pools.  How was the cave formed?  Here is a short, simple answer:

  • Precipitation mixes with carbon dioxide from the atmosphere and decaying organic material in the soil.
  • When Carbon dioxide is dissolved in water it forms carbonic acid. The carbonic acid begins to form holes in rocks, seeps into crevices and dissolves the rocks, especially limestone; but very slowly.  (Thousands of years)
    rock crevices and joints.
  • Cavities form and further sculpting can occur from water and chemical weathering.
  • After passing through limestone, the acid water contains a dis-solvable calcium carbonate.  As this solution de-gases through exposure to air by way of splashing, dripping or flowing, it loses carbon dioxide and deposits a solid mineral called calcite.
  • Calcite is the main mineral component in CAVE FORMATIONS, (speleothems).
Calcite, which gets its name from “chalix” the Greek word for lime, is a most amazing and yet, most common mineral. – See more at:

The SPELEOTHEMS in Colossal Cave no longer grow. This cave formed by water depositing limestone that has NOW disappeared.  Close by, in the same mountain park, are Arkenstone and La Tetera Caves with active growing formations.

dormant speleothems in Colossal Cave
crystallized calcium carbonate formations

The most abundant mineral in limestone is calcite (calcium carbonate).  The majority of limestone formed on ANCIENT ocean floors.

Calcite is a main component used by echinoderms, like sea urchins, starfish, and sand dollars to make their spines and skeletonsCalcium carbonate (calcite),  is found in the shells of marine organisms and truly is one of the MOST abundant minerals on earth!

In the marine environment, if the conditions are right, calcite is stable enough that it can cement together sediments and overtime make limestone.

calcite in the ocean water
limestone towers in the Atlantic ocean

On occasion another element may be present while calcite is being formed (ex: magnesium) and take the place of a calcium atom.

A less stable aragonite is a polymorph of calcite. They are both calcium carbonate but have different crystal shapes and symmetries.  The calcium, oxygen and carbon atoms in aragonite bond together differently creating a unique crystal structure.

Ok this is plenty of background information so now journey with us to Colossal Cave Mountain Park!

what to do in Tucson
The retaining wall and Visitor’s Center at Colossal Cave

The elevation of Colossal Cave Mountain Park is about 3,500 feet.  The temperature of the cave averages 70 degrees Fahrenheit.  No extra clothing is needed but feel free to carry water or a camera.

Colossal Cave in Vail, Arizona
walkway outside of Colossal Cave entrance

Frank Schmidt was monumental in the improvements and preservation of Colossal Cave by handing over his leases to the State of Arizona.  You can find information and historical photographs at La Posta Quemada Ranch Museum.

preserved Colossal Cave
Frank Schmidt statue at the cave


good picnics and kids activities at this Tucson park
bring the family and spend the day at this Arizona park

In 1879, Solomon Lick, the owner of the nearby hotel, was searching for stray cattle and discovered the entrance to this cave.

Arizona historical sites to see
professional guides take you through this historical landmark

Thousands of years ago Colossal Cave was used by Hohokam, Sobaipure and Apache Indians.  Travel down the road to the ranch museum for a fascinating display.

Indian historical sites in Arizona
Hohokam, Sobaipuri, Apache and Papago Indians used Colossal Cave

Two Indian skeletons were found in Colossal Cave by archaeologist Byron Cummings.

must see historical sites in Tucson, AZ
Colossal Cave has 363 steps

What is a crystal?  Simply put, it is a mineral that had a chance to grow how it was meant to be.  When and where crystals form depends on the type of mineral being formed.  Most crystals are found in areas, like caves, because they take a long time to form.

Crystals form from 2 processes:

  1. nucleation
  2. crystal growth in a saturated liquid solution

The majority of mineral crystals take thousands of years to grow.  The growth continues until the saturation is stopped or the cave dries out.

Most crystals in a cave are calcite or aragoniteSee my paragraphs at the top of this article.

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calcite in the cave

This cave adventure was called the Basic Tour.  The Ladder and Wild Cave Tours are more advance and take you through deeper less seen areas of Colossal Cave.   click here for Colossal Cave Tour Information

history of Colossol Cave in AZ, USA
experts determined this was an area for sleeping and even playing a game of cards

Your tour guide will tell the story of the bandits who hid out in Colossal Cave.  These outlaws even played cards in the Colossal Cave Living Room. Legend has it that the gold from the train robbers is still inside the cave!

Colossal Cave is a dry dormant cave
Ladder and Wild Cave tours
it is worth seeing Colossal Cave
watch your head inside the cave

Stay with the tour group.  Our guide really wasn’t kidding when she said the group might go left and you’ll go right and be lost for hours in Colossal Cave.

Take a peak in the wedding room! This Colossal Cave room maybe a beautiful area to renew our vows.

small wedding at Tucson's Colossal Cave
this room is for small weddings

Tectonic activity is noticeable in Colossal Cave.  Your guide will point out a fault in the earth’s crust.

Colossal Cave spelunking
Wild Cave Tours and Ladder Tours

Colossal Cave’s formations, speleothems, are created by the same water that dissolved the calcite in the limestone —- then deposited the calcite in other areas of the cave.

historical caves in Arizona
stalagmites and stalactites in Colossal Cave

Stalactites – “c” for ceiling – hang from the top of caves like icicles

stalagmites and stalactites
cave formations with labels

Stalagmites – “g” for ground – emerge from the ground like a traffic cone

Because Colossal Cave is DRY;  the appearance of these speleothems is different than living caves.

calcite deposits in Colossal Cave
formations in limestone caves

Calcite builds up into curtains and flows down cave walls like waterfalls.

cave adventures in Arizona
Stalactites hang from the ceiling in caves

The length and thickness of the calcite grows as the water continues to drip.  Stalactites (c for ceiling) can take thousands of years to form.

Layers of calcite build up into fluted curtains.
Layers of calcite build up into fluted curtains.
the best parks in Tucson, Arizona
breathtaking views inside Colossal Cave
over 350 steps inside the cave
our wonderful tour guide at Colossal Cave

We received bat education from our cave guide!  Bat poop is called Guano.  It makes good fertilizer and some companies use guano in lipstick.  Guano in lipstick is called guanomine.

FDR's Conservation Corp
Civilian Conservation Corps designated by President Roosevelt

In the 1930’s, a Civilian Conservation Corps designated by President Roosevelt worked tirelessly building the retaining wall outside and improving the inside of Colossal Cave.

President Roosevelts CCC at Colossal Cave
The Civilian Conservation Corps, CCC, put in the railings and stairs

The CCC, Civilian Conservation Corps, constructed the stairs, bridges and handrails inside Colossal Cave.  The historic office and museum of the CCC is located at La Posta Quemada Ranch.

Colossal Cave repairs and protection
Civilian Conservation Corps, CCC, helping Colossal Cave

While visiting Colossal Cave do adventure down the valley to La Posta Quemada Ranch.

The ranch at Colossal Cave Mountain Park has been a working ranch since 1878.

activities to do in Tucson
La Posta Quemada Ranch at Colossal Cave Park

Resident cowboys handle the ranch operations along with trail rides, hayrides, cookouts and horseback riding.

what to do in Tucson, Arizona
visit the historical Ranch at Colossal Cave Park

Colossal Cave Ranch headquarters has the museum, gift shop, bat and cave exhibits.  We ordered burgers, cooked out on the grill, and ate inside this Colonial Spanish-style historic house.

The cowboys at Colossal Cave Mountain Park ride you through the Historic National Mail Stagecoach Route.  Reservations are required.  (call Colossal Cave )

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Horseback riding and Cowboy cookouts at the Ranch
La Posta Quemada Ranch in Arizona
history at the museum in the Ranch house

Several movies were filmed inside and around Colossal Cave.  See the movie exhibit inside the Ranch Headquarters.

disney movie at the cave
movies filmed inside Colossal Cave
history of Colossal Cave outside of Tucson
Night of the Lepus movie at Colossal Cave

Time was spent observing the Desert Tortoise.  These are one of the hardiest creatures of the Arizona Sonoran Desert.  Some even call tortoises “living dinosaurs”.  The Colossal Cave Mountain Park Tortoise exhibit is well done!

things to do at Colossal Cave near Tucson
Tortoise exhibit at the ranch

Colossal Cave and the historic La Posta Quemada Ranch are listed on the National Historic Register.  When you visit be sure to enjoy a Desert Spoon Burger!




Author: tjsgarden

We are a family that loves the Arizona Desert. A lot of research and team efforts go into our articles and photos. Come discover the beauty and mystery with us. Don't forget your sunscreen!

7 thoughts on “Journey inside Colossal Cave Mountain Park – Arizona’s dormant cave”

  1. Hey TJ, are the articles on the other two caves going to be posted? There’s been alot of interest generated with the the local caving groups, but we’ve been denied access to both caves. I’m assocaiated with Central Arizona Grotto and the NSS. Your more then welcome to email me. thx

    Liked by 1 person

    1. That is a great question! I’m currently working on an article for both Caves. We are paying a visit to Colossal Mountain Park area this weekend and I will check the research library and museum to see if there are any new updates before I post my articles on Arkenstone and La Tetera Caves.



      1. Yes, Arkenstone and La Tetera , Pima County closed them off to cavers and scientist, can’t really get a straight answer why. Some of the guys in SAG Southern Arizona Grotto have some great photos.


        1. I’ll see what information I can get from the managers at Colossal this weekend. Boy, sure would love to see your photos! This has been really difficult to research and even harder to get photos.


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