Coquina Limestone

 Although rare in Central Texas, "coquina" limestone is occasionally evident, generally as part of the sedimentary deposit categorized as the "Cow Creek Limestone" geologic formation.  Although it can be found in other "limestone" deposits.  Coquina implies fossil-dense limestone.  Limestone implies calcium carbonate rich material, and sea shells are calcium carbonate rich material.  Therefore a coquina is a form of limestone.  As with most limestone materials, coquina can be a detrital limestone (shell-dense soil transported during deposition) or non-detrital (shell-dense beach buried rapidly in place).

Various terms have been developed to describe fossil-dense limestone, therefore terminology can be confusing or even defined differently be different people.  In general terms we might commonly use:

"Coquina": A limestone sedimentary deposit formed predominantly by marine shell animals and sand.

"Coquinite": A stong cemented coquina (rock), likely formed from notable burial under subsequent sedimentary deposits.  Lithification by compaction.

"Coquinoid": A coquina where sand is more abundant in the matrix.

"Hash": Fossil hash or shell hash are terms used to described a coquina with notable variable (mixed) animal types and shell condition.  High variability and condition of the animals at the time of burial generally implies a high hydraulic energy environment that broke up the sea fauna to produce a bed of random composition.

The samples at right were identified as coquina (or more likely coquinite) found in Texas, offered for sale on ebay.

This is a photograph of coquina found in Florida.  This has the structure of a detrital deposit (deposition from high energy event).









High energy events producing fossil hash could conceivably be from large waves (meteor impact; earthquake) or underwater landslides caused by any number of possible events.

When a coquina is discovered with relatively intact postmortem shells (split bivalves) and low variability, it might imply rapid burial of a shell-dense beach.  Some shell-dense beaches exist around the world including in Australia and the Caribbean.  The shells wash ashore and collect over time.

Catastrophic Geology: Case 13 - Burlingame Canyon

In 1926, a diversion ditch exposed to relatively high water flowrate and volume produced a 1500-ft long 120-ft deep canyon in just 6 days through hardened fine-grained (silt, clay, fine sand mixtures possibly) and occasionally gravelly, sedimentary deposits characterized as the "Touchet" geologic formation".  These deposits are from "slackwater" produced after the massive Missoula flood.  The huge canyon exposed uniform thickness beds (layers) of the slackwater deposits, indicative of pulses of flood backwater from the catastrophic flood event.  The beds are also characterized as rhythmites or rhythmically bedded material.

The canyon is in the current Wall Walla river valley in Washington State.  The rhythmites are 330 feet thick, indicating the massive nature of the Missoula flood and the geologic consequences of such a catastrophic event.

This is another example of the power of water and the catastrophic impact it can have on geology.  The "Touchet" beds were formed from a catastrophic event, and the Burlingame Canyon through them was formed by a catastrophic event.  You do not need millions of years to produce the landscape you see around you.

Catastrophic Geology: Case 12 - Rock Erosion

Rock erosion occurs much faster than previously conceived or perceived.  Very steep slopes or vertical faces (bluffs) are inherently unstable over time.  And no it does not take "millions of years".  The rock formations we see today are constantly experiencing rock mass wasting (erosion) due to weathering processes.  Catastrophic collapses routinely occur, altering our landscape.

"London Bridge"  on the Australian coastline collapsed in 1990, stranding 2 tourists on the outcrop who had to be rescued by helicopter.  Images were presented in the 2015, No. 2 issue of Creation Magazine.

In 2009, the "Island Arch" collapsed.  The rock formations you look at today are not "millions of years old" or exhibits of "timeless eternal looks", they have changed significantly since their initial exposure.










In 2005, one of the "12 Apostles" suddenly disappeared:

The rate of rock mass wasting observed is one of the many pieces of evidence that refutes the concept that the earth could be "millions of years" old.

Arches National Park in Utah also exhibits rapid rock mass wasting.  In 2008 the famed "Wall Arch" collapsed.  The famed "Landscape Arch" will collapse at any moment, with some progressive collapses already observed.  Since 1970, 43 of the park's arches have collapsed, providing evidence of relatively rapid changes to rock geomorphology.