One of the most spectacular places I visited while growing up was Carlsbad Caverns National Park in New Mexico.  The accessible portions of the caverns open to the public reach depths of around 800 feet below the surface, and the magnificent "Big Room" is a chamber nearly 4,000 feet long and 255 feet high.

Nearby, in the same National Park grounds, Lechuguilla Cave reaches depths of over 1,600 feet.  The staggering extent of its incredible winding passages is perhaps best appreciated by viewing a 3-D computer map of that cavern system (not open to the public).  One such computer map can be seen in the video embedded below:

These caverns, like many other "solution caves" found on our amazing planet, exist inside of massive limestone formations.  Where did so much limestone come from?

The conventional explanation for the origin of limestone involves warm, shallow inland seas, because conventional geologists argue that almost all limestone deposits resulted from the deposition of the remains of shallow-water marine animals (such as corals, as well as some crustaceans and algaes) that incorporate limestone into their body structures.  

In order to account for limestone deposits that are thousands of feet thick, they must come up with speculative scenarios in which these seas stayed shallow while the geology below them slowly subsided, enabling the successive creation of thicker and thicker deposits over millions of years.  These proposed scenarios are recounted with absolute authority (as if we are certain that this is what happened) and peppered with impressive-sounding terminology.  An example of one such "history" can be found here (describing the supposed processes that created the "reef limestones" that now house the vast caverns of Carlsbad and Lechuguilla).  The National Park Service webpage describing the geology of Carlsbad Caverns similarly refers to a "the uplifted portion of an ancient reef that thrived along the edge of an inland sea more than 250 million years ago during Permian time."

As we have seen in previous blog posts (see for instance "Just So Stories: The White Cliffs of Albion"), hydroplate theory founder Walt Brown provides powerful arguments that the conventional theory about earth's limestone is mistaken, and that the limestone on our planet is compelling evidence of a catastrophic global flood in earth's past.  In an entire chapter dedicated to discussing the origin of limestone in his book on the hydroplate theory (which is available for all readers to access on the web here), Dr. Brown points out that the conventional theory for limestone runs into numerous problems.

One big problem that he cites is the fact that the formation of solid calcium carbonate (CaCO3, various crystal forms of which make up the limestones of the earth) releases a carbon atom, and the amount of limestone on earth today makes the "shallow sea" hypothesis difficult to maintain (see formula below).  
 H2O (l) + CO2 (aq) +CaCO3 (s) <==> Ca (aq, 2+) + 2HCO3 (aq, 1-)
After pointing out the basic two-way chemical formula by which water dissolves limestone (left side of the formula moving to the right side of the formula) or by which limestone precipitates out of water (right side of the formula moving to the left side of the formula), Dr. Brown writes:
Here is the problem. The above chemical equation shows that for every carbon atom precipitated in limestone, a carbon atom is released in CO2. At the earth’s surface, this gas enters the atmosphere. Had all limestone slowly precipitated in surface waters, as much carbon would have been released into the atmosphere (as CO2) as was precipitated in limestone (as CaCO3). The earth’s limestone contains more than 60,000,000  × 1015 grams of carbon. That amount of carbon in the atmosphere and seas would have made them toxic hundreds of times over. Today, the atmosphere and seas contain only (720 + 37,400)  × 1015 grams of carbon. [from this page in Dr. Brown's online book].
In other words, there simply is not enough carbon in the seas and air today to believe that limestone precipitated primarily in warm shallow seas the way the conventional theorists argue.  Based on the amount of limestone found on earth, the carbon released would have made our planet a very different place if that conventional theory were correct.

Another problem Dr. Brown notes is that limestone-forming marine life today thrives primarily in the shallow portions of the warm oceans within 30 degrees of the equator.  However, limestone is found all over the globe today.  Further, he points out that the typical limestone particle is very small, and that natural forces could not be expected to reduce organic limestone from coral or other marine animal shells to such small sizes (as the particles become smaller and smaller, they become increasingly difficult to break down further).  He also notes that very high magnification available in more recent years shows that the structure of most of the limestone on earth is quite different than organic limestone found in sea organisms (see this page in his online book).

Instead, Dr. Brown argues that most of the limestone found around the globe is of inorganic origin, precipitated in the water that was trapped deep under the earth before it violently escaped to initiate the catastrophic flood.  His theory, which explains the evidence we find around the globe better than the conventional explanation, proposes the following series of events:
Supercritical water (SCW) readily dissolves certain minerals and other solids. [See pages 120122.] As temperatures rise or as pressures drop in the SCW, these dissolved substances precipitate as “snow.” In the years before the flood, tiny limestone particles precipitated to the subterranean chamber floor as the temperature in the SCW steadily rose. During the flood, the pressure in the escaping water rapidly dropped, so more limestone precipitated and CO2 gas escaped. Simultaneously, limestone sediments on the chamber floor were swept up to the earth’s surface, where liquefaction sorted the limestone particles into more uniform layers. [See pages 186197.] 
Sediments, eroded during the initial stages of the flood, settled through the flood waters all over the earth. After most of these waters drained into the newly formed ocean basins, limy (CO2-rich) water filled and slowly migrated through pore spaces between sedimentary particles. 

Plentiful amounts of CO2 in the atmosphere after the flood provided the necessary “food” to help reestablish earth’s vegetation, including forests. As plants grew and removed CO2 from the atmosphere, surface waters released additional CO2, thereby precipitating more limestone. Limestone that precipitated between loose sedimentary grains cemented them together into rocks. Earth’s surface waters are still huge reservoirs of CO2. Oceans, lakes, rivers, and groundwater hold 50 times more CO2 than our atmosphere. 

Tiny particles of precipitated limestone are excellent cementing agents when near-saturation conditions exist. Smaller and more irregular particles of limestone readily dissolve; larger particles grow, sealing cracks and gaps. Precipitation within a closely packed bed of sediments (cementation) occurs more readily than precipitation outside the bed. [from this page in Dr. Brown's online book].
This scenario explains the great thickness of many of the limestone formations around the world, including the one that is home to the Carlsbad Cavern and Lechuguilla Cave.  His theory also explains how the earth's limestone caverns (some of them, like Carlsbad, with enormous chambers) and majestic stalagmites and stalactites could have formed in thousands of years following such a catastrophic event, rather than the millions of years usually proposed by conventional theorists:
Acidic groundwater, plentiful during the centuries after the flood, frequently seeped into cracks in limestone rocks, dissolved limestone, and formed underground caverns. As ventilation in caverns improved and plant growth removed CO2 from the atmosphere, CO2 escaped from this groundwater. Large quantities of limestone precipitated, rapidly forming stalactites and stalagmites worldwide. [From this page in Dr. Brown's book].
Dr. Brown points out that even today, when stalactites and stalagmites typically grow much more slowly than they would have immediately following the flood (when large amounts of water were draining through freshly deposited limestone), certain conditions can cause rapid formation of limestone features.  He cites Jerry Trout, the National Cave Manager for the  US Department of Agriculture Forest Service, as filming stalactites that grew several inches in a matter of days.

The origin of the earth's abundant limestone is a matter of great interest and one that can draw helpful lines of distinction between competing theories about how our geology came to look the way it does today.  Here again, the evidence appears to be difficult to reconcile with conventional theories, but to be quite consistent with the forces expected to have been present before, during, and after the flood according to the hydroplate theory explanation.