The Lady Hides Her Age. EarthCache

This Earth Cache is designed to be a learning experience. Explore the surroundings. Read up the description. Do additional research if you feel so inclined. There is a list of tasks to be undertaken to enrich the learning experience. Please respond to these tasks and submit your responses to the CO via the message facility of the app, or by email.

You may claim the find, but must have responded within 14 days of claiming your find.

Any find logged without a corresponding response after that time may be deleted at the sole discretion of the CO.

There is secure Parking available at the Parking waypoint for a nominal fee (R25 per day with some concession cards applicable as at June 2018)

Access to the beach is via the entertainment center. Alternative access may be possible but is not recommended. This Earth Cache is situate about 3 km from the parking, on the beach. Please be aware of the tides, as high tides might restrict getting there or back. You are urged not to deface the structures, and to respect this proclaimed heritage site.

Above all else please enjoy this unique learning experience.

No Self Respecting Woman will readily reveal her age when asked, and so to with Mother Earth.

This Earth Cache seeks to explain, in very broad strokes, the determination of Earth Age, and then exposes you to one of the changes.

A noticeable change in the age of Mother Earth, not unlike the wrinkles you noticed around your own mother's face when she turned from being 49 years old to 50 years old, for example. Or perhaps the added creases upon your own face!

With Mother Earth these wrinkles are not readily noticeable at the time of the birthday, but are easily recognisable long after the birthday had passed.

In talking of Earth Age, Geologists term these wrinkles

UNCONFORMITIES.

This Earth Cache will explore this unconformity, and will try to picture the younger Earth, and explain why these 'wrinkles' appear. But, as with any good exploration, there may be a twist at the end!

Background

As you can might imagine, it is mighty difficult to pin the old lady down to an age. Way back in 1658, the Irish Archbishop James Usher determined that the Earth was created around 4004 years before this era, a study that has 'evolved' into the currently accepted value of the Earth being some 6000 years old. This theory is supported by a number of scientific studies, and has a large support.

An alternative determination of the age of the Earth uses the tools of the Vedic belief and follows the ancient evidences of the Hindu tradition. By following the sacred texts, and referencing various known age records within the historical writings, and by substituting the recorded ages of figures in the broader narrative, these scientists are able to place the age of the Earth at around 1,84 Billion years old.

Following in the footsteps of the enlightened supporters of the school of Reasoning, other scientists hold that if a premise or model can be supported by unrelated evidence, and can be repeated, that premise must be fact. This approach is well supported, and holds that the age of Mother Earth is 4.6 Billion years! That is 4,6 Thousand Million years.

Reality check:

One million seconds = 1 week, 4 days 13 hours 46 mins and 40 sec.

(You are not required to carry out this experiment to claim your find!)

And that is just One million. It is held that Mother Earth is 4,6 Thousand of them!

So how do Geologists measure this enormous time? What tools are used to mark the passing of years? Obviously candles and wrinkles may work for older Humans, but what is used to measure the age of the Earth?

Tools of the Trade for the Geologist

Radiometric Dating. This method refers to the counting of the neutrons within an elemental isotype. Dependable and repeatable, this method only really becomes useful when there is an igneous or metamorphic rock sample to measure; Provided that the rocks are composed of an element that create an isotype.

Paleomagnetic measuring. This method refers to the comparing of magnetic alignment from iron rich rocks against each other. Useful for Tectonic measuring, it adds little value to the sedimentary rocks which cover about 85% of the Earth.

Biostratigraphy, This is the process whereby organic fossils and the remains of organic matter found within the rock are used to determine the age of the rock. It is a process that bridges the dating of life matter with that of determining the age of Mother Earth.

Narrative, or Oral Evidence.This method of determining age is only of value in the latter part of the current era of the Earth's existence. It involves detailed analysis and extrapolation of social communities and applied such to models hypothesizing possible development. For example, the belief that the Earth is about 1,3 Billion years old is based primarily upon the Vedic almanac and writings. The use of this tool is bound by the communicative abilities of the life forms on Earth at that time.

The Geological Time Scale.In order to comprehend the enormous space of time in regards to Mother Earth, defined blocks of time have been agreed upon, and are used as a foundation for further research. The age of the Earth is divided into TWO Eons – Precambrian (up to 500 million years ago) and thereafter the Phanerzoic Eon. The current Eon is divided into 3 Eras, known as Paleozoic, Mesozoic, and Cenozoic.

Each Era is further split into Periods, examples of which are the Carboniferous, Permian, Triassic, Jurassic, Cretaceous, Tertiary periods. And each Period is further sub-divided into Ages.

"International Classification Standard Table"

Stratigraphy. This tool looks at the study of sedimentary strata, or beds of sediment. It uses the analysis of sedimentary beds to determine conditions of space and time when such deposits are made. There are 3 recognised laws of the strata nature of sedimentary lithification, and 3 corollaries to those laws.

1. Law of Superposition. The lower strata of sediment is the oldest.

2. Law of Original Horizontality. All sediment is laid in a horizontal plane.

3. Law of Lateral Continuity. Sediment laid down will be continuous until there is an interruption.
   
   This leads on to the first of the 3 corollaries,

And so, having an understanding of the terminology of the Earth aging process, and having been introduced to the tools used to aid the measuring of the Earth age, we now turn to the focus of this Earth Cache.

The Santonian / Campanian Uncomformity of the late Cretaceous Period during the Mezoic Era, as evidenced at the Mazamba Cretaceous Deposits.

As an aside, and to break the intensity, the Campanian Age was named after the region in France where this age was defined. The same region that introduced Champagne to the world. Who said Geologists do not have a sense of humour?

An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger, but the term is used to describe any break in the sedimentary geologic record.

An unconformity represents time during which no sediments were preserved in a region. The local record for that time interval is missing and geologists must use other clues to discover that part of the geologic history of that area. The interval of geologic time not represented is called a hiatus.

At the GZ you are faced with a lateral exposure of the Santonian and Campanian unconformity.

To fully comprehend this 'change in age of Mother Earth' some perspective should be grasped. This area is the Southern most edge of the Mozambique Basin, which stretches from here up to central South Mozambique. East Antarctica and Australia had already broken away from the Nubian Plate (Africa) and along the Eastern edge of the continent, India and Madagascar had recently separated and were drifting Northeast in a Tectonic race to reach their current positioning.

In terms of upward pressure, the Lebombo mountain range had recently thrust upward and tilted toward the East, and the Basalt larva flows from the Drakensburg range were already undergoing rapid erosion.

The climatic conditions during the Santonian age, starting from around 87 Million Years Ago (MYA) was one of turbulence. High temperatures and unrestricted wind channels, with a large pool of shallow water, resulted in severe tropical activity. This would bring with it the abundance of thunderstorms, hurricanes and cyclone activity. This precipitation increased the veracity of the run off and thus heightened the formation of the Eastern escarpment. It also contributed to the unconformity before you.

Using data from boreholes throughout the Mozambique Basin, it can be determined that the depth of the Santonian rock is measures around 64 meters. These measures are consistent with boreholes in Southern Tanzania, Southern Namibia, and the Northern Mozambique Basin. Of interest, the core samples from boreholes within South Africa – at Orange River, Bedersdorp, Platuurs, Gansoos, or Algoa basin; none show evidence of the late Santonian rock although they do record a shorter measure of earlier rock. And so it is consistent that there is a strata of substantive Santonian rock that lays across the Southern edge of Africa.

The nature of this rock is made up of well rounded grains held together by a simple cement of calcite with little other inclusions. And this would be consistent with the turbulent conditions of deposition. And would explain the relative ease of erosion, as seen by the cave formations at this site.

Turning to the younger Campanian sediment, the difference is glaring.

Campanian age rock is made up of mud. It is a mudstone created from a still and stagnant depositional medium. The grains are semi rounded, with sharp and angular edges, and the cementing substrate has a higher proportion of cohesive properties. This rock has a higher resistance to erosion. It is also far more chemically varied than it's predecessor.

This period of time, up to 83½ MYA, saw the magnetic field of the Earth remain constant. The whole Cretaceous Period, from 145 MYA to 83 MYA has not a single variance in magnetic readings. As this is a relatively new approach to geology, the significance cannot be determined, but suffice to say that on average the Earth's magnetic orientation waxes and wanes, and in fact reverses, roughly between every couple of hundred years to 80 million years.

Yet from 145 MYA to 83 MYA the magnetic field of the Earth was stable, without reversal.

Of more use is that the Campanian age ushered in the discovery of nano fossils. Core samples have produced evidence of a previously unknown fallio, the Broinsenia pacca pacca. This primitive mollusc was first found in early Campanion rock, and is used as an accepted measure of age.

The conditions you see before you, with the Santonian and Campanian unconformity, are reflected in most of the core samples taken with respect to these Ages.

And the ratios of Santonian to Campanian samples remain constant.

Except here.

(Remember mention of a mystery earlier on? Here it is...)

While elsewhere the average width, or depth, of the Campanian Age rock lies between 7 to 15 meters, here at the GZ, the depth of the Early Campanian Rock is only 7 cm.

Why do you think that is?

Is it :- due to some endemic erosion episode that removed thousands of years of sediment? Or due to some unique marine activity that dislodged the settlement of thousands of years of sediment only at this site? Or due to a marginal upliftment limited to this end of the Mozambique Basin, perhaps part of the Indian Ocean creation? Or due to a random quirk of chance that placed data deficient samples within the samples measured? Or does it have something to do with the static magnetic field for the entire Period?

Science is unable to account for this. Yet.

References:

Reappraisal of foraminiferal assemblages of the Santonian-Campanian Mzamba Formation type section, and their correlation with the stratigraphic succession of the KwaZulu Basin. Ian K. McMillan 2008

PALAEONTOLOGICAL TECHNICAL REPORT FOR KWAZULU-NATAL Dr. Gideon Groenewald 2012

http://palaeos.com/timescale/timescale.html/

Timing and geometry of early Gondwana breakup Wilfried Jokat, Tobias Boebel, Matthias König, Uwe Meyer 2003

Society For Sedimentary Geology www. Sepmonline.com /

https://www.thoughtco.com/ K. Kris Hirst

Tasks.

To retain your FOUND status, please respond to these tasks within 2 weeks.

1. In your opinion, can you describe how the caves and alcoves along the cliff face came about?
   
   

2. If you were to count up to one Billion (Thousand millions) at one number per second continuously, and if you started at Midnight on Saturday 1^st June, 1986; when would you reach One Billion?
   
   

3. Looking at the strata below the vegetation line, and in the cave roofs, several shells and foreign bodies are to be found. From which Age do these intrusions belong, Santonian or Campanian? And why?
   
   

4. Why do you think the depth of Campanian strata is noticeably thin at this location?
   
   

5. (Optional) You may wish to take a photo of you and your team and include it with your log.