Friday, March 28, 2008

Ram Sethu – issues on volcanism and yuga classification.



I am not a scientist, nor a technical person
to analyse the scientific aspects of Ram Sethu.

Yet I dare make observations / comments on the nature of Ram Sethu,
purely out of my habituated instinct to relate and rationalize
what I absorb from the Hindu scriptures with
what I observe from the outside world.

For a scientist, these observations and write-ups may appear absurd and a non-sense.

But a little in-depth analysis of our scriptures had convinced me
that they contain the keys to all questions, problems and even non- problems.


They contain replies or leads to any issue that may arise at any time period.
Based on this realization, I proceed to write more on 2 issues,
from the point of view of scriptures.

The geological history.



One such issue is about the geology of Ram Sethu.

Certain rationalizations from scriptures were made by me in my earlier posts,
particularly, in "Volcanism at Sethu"
http://jayasreesaranathan.blogspot.com/2008/02/no-aryan-dravidian-divide-it-was-one_08.html
and on the formation of Bay of Bengal.

From Ramayana it is deduced that that Rama Sethu area
contains volcanoes such as Mainaka
which grew in size when Hanuman crossed the sea.
Mainaka is situated on an opening on the mantle below.
Even Rama was desisted by the Ocean Lord from disturbing this sector.

The Ocean lord who on his own volition,
directed Mainaka to help Hanuman in Raama kaaryam,
did not show up when Rama himself sought his help
until Rama threatened to break the sea floor at the area of Ram Sethu.

This contradictory stance of the Ocean god can be understood from the rationalization
that he could not give in to Rama's expectation
as long as it was about breaking that area to make a way.

This goes to show that this sector was not to be disturbed for any reason,
even if it is for Raama kaaryam!


The report given at the end of this write-up
by Mr. K. Gopala Krishnan Director (Retd.) Geological survey of India,
on the geological and volcanic issues at this area
vindicates the information gathered from Ramayana.

He has noted the following geographical signatures at Ram Sethu:-
· (1) It rises as a Very Steep Wall-like Feature from the Gulf of Mannar
· (2) It is a "Strait" joining two seas-Palk Bay and Gulf of Mannar
· (3) It is an "Isthmus" connecting two land masses – Rameswaram and Thalai Mannar islands under the sea.
· (4) It is a unique curvilinear feature.
· (5) It is nearly 17 Lakhs year old.
· (6) It is a "Barrier Zone" that separates two contrasting seas- the shallow and turbid waters of Palk Bay from the deep and clear waters of Gulf of Mannar.
· (7) It is a "Barrier / Protection Zone" against "Tsunami" impacts.
Point number 1 makes me relate it to a feature- supposed to have been man-made
from the account in Ramayana.

The 60,000 sons of Sagara went ahead digging up
one square yojana per person
and dug around Srilanka, giving it the present shape.

They first stopped north of the present Ram Sethu,
then went digging around Srilanka and ended up south of Ram Sethu
which is now called Gulf of Mannar.

The steep slope on the side of Gulf of Mannar might be because of this.
The patch that connects India and Srilanka had been left untouched,
upon which Ram Sethu must have been built by Rama.



If the narration in Ramayana of Sagaras' digging of the area
where now stands the Bay of Bengal is
actual and not symbolic or allegoric
the following must be looked for, by the researchers in this field.
(1) Whether the depth of Bay of Bengal is uniform throughout.
(2) Whether the depth at Gulf of Mannar is a continuation with the rest of Bay of Bengal
(3) Whether the ocean floor of the Bay of Bengal is more or less free of undulations.
(4) Whether a fracture or joint of tectonic plates occurs at Ram Sethu



If the sagaras' feat is true, the following must be answered.
If the Himalayas had come into existence
as a result of push by the plate on which India stands (Lemuria?),
why do the Himalayas stretch until Myanmar?

Does it mean the entire landmass that pushed up the Himalayas
was like the one shown in the picture below? (red bordered edges of the landmass)




The movement of Indian plate colliding with Eurasia to form Himalayas is depicted like this:



But the Indo-Australian tectonic plate is something like this:


(The Indian plate with Bay of Bengal shown in red and Australian plate in orange).
The Bay of Bengal part of the Indian plate is indeed pushing against the Burma plate and this is bordering on Nicobar islands.
http://en.wikipedia.org/wiki/Bay_of_Bengal
The information from Sagaras' episode is that this part of the plate was a continuation of land mass of India and was dug by them later.

The marine-archaeological studies on the floor of Bay of Bengal (in the link below) also show channels and valleys on the sea bed. These corroborate any of the two episodes - sagaras digging the earth and Ganga flowing through channels dug and / or the once uplifted land of Bay of Bengal in the Kalakeya episode with Agasthya draining the waters of the Bay.



http://drs.nio.org/drs/bitstream/2264/449/1/J_Indian_Geophys_Union_4_185.pdf
I happened to get the following picture in the internet,
featuring the sunken land of Kumari,
and its location in Lemuria.



The formation of Srilanka (later) out of this landmass
looks live a carved out structure and unnatural,
considering the deep seas around it.

On the other hand, the narrow, rectangular bowl of Bay of Bengal
exhibits a peculiar formation.
It looks more appropriate to have Bay of Bengal
also as part of land mass of Lemuria
that is pushing Eurasia.



The bowl of Bay of Bengal must have come into existence later,
which we find as the handiwork of Sagaras, as per Ramayana.



Time factor – Yuga classification.


This is the other issue
that is making scientists who say
that Ram Setu is 17 lakhs years old,
not to concede that it is man-made.

Can a man-made structure on seas survive that long?

Here again we get some inputs on time scale from Scriptures.

Treta yuga happened 17 lakh years ago.

This is a true statement as per scriptures.

But treta yuga of which of which classification is the question.

Because Yuga classifications happen at different levels.

Yuga in Sanskrit means Yugma a double or duo or twin.

Whenever an ascent and a corresponding descent exist together,
it is known as a Yuga, as per Vedas.

A day is a Yuga, because it constitutes a day time and a night time.

A month (lunar) is a Yuga,
because it constitutes waxing and waning moon
(shukla and Krishna pakshas)

A year is a Yuga, because it constitutes 2 ayanas.

The 5 year period having two 2 and a half year period of extra lunar month, is a Yuga.

This is based on equalizing the solar and lunar months.
The sun takes 365.25 days to move from one star and to reach the same star
which makes a year.

But the moon finishes this round in 354 days in a year.
The difference between these two is 11.25 days.
In this way, for every two and a half years,
the moon finishes an extra month of 29.15 days.

This is known as Adhika masa.

One round of Adhika masa coupled with another round of adhika masa,
makes it a Yuga,
known as “Pancha varshathmaka Yuga”-
the yuga of 5 years.

This is the yuga identified by Vedas for human beings,
- for fixing the time for doing rituals.

The details of this can be read in 7 & 8 mantras of 103 sukta at 7th mandala of Rig veda.

It is from the principle of ‘Ahorathra’ (day-night pair),
the yugas such as satya and Treta are drawn, says Rig veda samhita (1-103-4)



Sayanacharya in his commentary to these mantras says
that the yuga classification (Pancha varshathmaka Yuga)
is for use by human beings.
Satya and treta yuga are at sun’s level.

That is better known as ‘Divya’ yuga.

Div’ means light.
It is about the stars that emit light.

At the level of stars, 2 kalpas make 1 day of Brahma deva
It is like this.



1 souramana (year) = 12 month sojourn of the Sun around the zodiac.
43,20,000 souramana = 1 chathur Yuga = 4 yugas (satya + treta + dwapara + kali)
71 Chathur Yuagas = 30,67,20,000 souramana = 1 Manvanthra
(since every manvanthra is followed by a period called sandhi which is equivalent to 1 satya yuga),
1 manvanthra + 1 sandhi = 30,67,20,000 souramana.
Like this,
14 sandhi + 14 manvanthra = 4,31,82,72,000 souramna
1 kalpa = (14 sandhi + 14 manvanthra) + 1 kalpa sandhi
= 4,32,00,00,000 souramana
1 kalpa = a day of Brahma deva = a night of Brahma deva.

This is roughly equivalent to 20 rounds of the Sun
around the Galactic center
(Modern science calculates 1 round to be roughly around 220 million years)


At this level of reckoning only, treta yuga contains 17 lakh years!

The basic unit is 4,32,000 years.

This is the duration of Kali yuga.

Double of it is Dwapara yuga.

Three times of it is Treta yuga and

4 times of it Satya yuga.


The major geological and cosmic events are related to this yuga classification.
(The avatars such as matsya, koorma and varaha are related to these yugas)

As such the raised formation under the sea at Ram Sethu
may have happened in Treta yuga (divya yuga)
as a result of volcanism or eruption of the mantle.

This was utilized for laying a bridge
in the treta yuga at human level of yuga classification!



The division of 4 yugas is in the ratio of 4:3:2:1.

So far I have not come across any pramana for when the current yuga started.

But it looks logical that the beginning of Kali yuga at cosmic scale (divya yuga)
coincided with the kali yuga in Dharma scale. 

There are quite many verses to say that Kali yuga started after the departure of Krishna.

First let me make a split –up detail of the mini yugas on the basis of 4:3:2:1

One half of this 1 cycle, namely 28,800 years is day and the other half is night.

In other words, it could be equated to ascending and descending
phase of this cycle.

This number is 14,400 years.
Splitting this into 4 mini yugas,
we get 5760, 4320, 2880 and 1440 as the number of years
in the order from satya yuga to kali yuga

Taking the year 3102 BC as the cut-off year as it has been accepted
(scripturally and astrologically – I will post an account on this later)
as the year of
Krishna’s departure and the advent of Kali,
let us calculate the years of the previous mini-yugas.

3102 + 2880 = 5982 BC when Dwapara yuga started.
5982 + 4320 = 10,302 BC when Thretha yuga started.
10,302 + 5,760 = 16,062 BC when Krutha yuga started.


That is, the present cycle of 28,800 years (in our words, the mini chatur yuga)
started in the year 16,062 BC,
assumed to be the day time of the cycle (ascending).


By deducting the years for mini kali yuga, 1440,
we arrive at the year (3102 BC - 1440 = 1662 BC)


That is, from the year BC 1662 one ascending phase got over
and the descending phase started.

From this the duration of yugas, current and future are like this.
1662 BC + 5760 Years = 4098 AD (satya yuga ends)
4098 AD + 4320 years = 8418 AD (Thretha yuga ends)
8418 AD + 2880 years = 11,298 AD (Dwapara yuga ends)
11,298 AD + 1440 years = 12,738 AD ( Kali yuga ends, The cycle ends)

At AD 2008, we are now in Satya yuga
in the descending phase. 

One crucial correlation drawn from the above calculation is that
the decline of Vedic religion and
the landmass of Bharathavarsha where Vedic /Aryan society flourished
started from BC1662.

The yuga classification is applicable to Aryavartha only, as per texts.

Sanjaya says this while explaining the nature of landmass and people
to the king Dhritharashtra,
after getting the divine eye to see the war.
(Jhambhoo dweepa nirmana patalam in Bheesham parva)

From this analysis we can deduce that
Treta yuga when Rama was born,
happened between BC 10,302 to BC 5982

The astrological and cosmic map deducing Rama’s times fall within this period.

There may be some differences in the computations to arrive at an exact date of Rama’s birth.

But it does come within this period as per Saptha rishi mandala classification.

A structure such as Ram setu built in this period
is sure to survive the vagaries of nature
for as long as 8000 years that had gone by.


So it is not right to dismiss Ram setu as man-made structure on the basis of time scale.

The text of Mr K. Gopala Krishnan’s comments / report is given below .
My thanks to Dr S. Kayana raman who sent this to me.

-Jayasree

Also read


SSCP: illegalities and failures in geological planning endangering geo-stability
Comments from K. Gopala Krishnan Director (Retd.) Geological survey of India (20 March 2008):

The two reports submitted by us, one the Geological and geotectonic setting of the Palk Bay – Gulf of Mannar area and its relevance to SSCP (22 Pages with 24 figures and one table) and , the other one, Geoscientific status of Rama Sethu ( 9 pages 11 figures) have been completely ignored by the Committee of Eminent Persons (CEP) inspite of our personal presentation.
In these reports, we raised certain serious concern over some specific aspects of SSCP

1. No detailed Geo-technical evaluation report for SSCP as a whole has been prepared by any competent geo-scientific agency as a part of pre-project studies. A report entitled report on geological and geo-technical assessment of the sub-strata for the proposed Sethu samudhram Navigational channel submitted by National Institute of Ocean Technology (NIOT) does not cover all the necessary aspects of geotechnical studies –
a) Study of a geological, structural and geotectonic features including sesimotectonic signatures (Earthquakes).
b) The determination of the strength and stability and or weaknesses of the foundation and walls of the proposed canals.
c) Rendering Geo technical advise to the project authorities for any remedial measures and treatments to be given to the weak planes in the foundation and wall structures as well as the type of materials to be used.

2. No detailed geo environmental assessment has been prepared for SSCP. The EIA report of National Environmental Engineering Research Institute (NEERI) does not include the following aspect of Geo-environmental assessment such as
a. Assessing the Geo-environmental resource potential – Minerals, Ground Water, natural geological and geo-morphological features as well as associated natural geological processes.
b. Environmental Impact Assessment of impacts likely to be caused to the above resources as well as to the environment as a whole.
c. Geo-environmental Management Planning defining the methodology and remedial measures for deducing the impacts for sustainable development.

3. Out studies indicated that there are 4 sets of active faults in the project area which are active during the present day producing vertical as well as lateral movements of blocks. The surface manifestations of these movements have brought in subsidence, submergence and slump structures.

4. Out studies also point to the existence of higher heat flow signatures in and around the project area which are reflected in the form of hot water springs on the surface. The source of this heat flow is related to the buried recent volcanic vents that are reported in Gulf of Mannar and off Pondicherry.

5. Geophysical studies indicate that SSCP area is vulnerable to earthquakes. Epicenters of recent earth tremors of moderate magnitude ( 4to7 M) are recorded in Gulf of Mannar, Palk Bay and off Pondicherry Coast.

6. Our studies also indicated that Tsunami waves will move with high intensity following lateral movements of active faults.

7. Our studies also indicated various geo-environmental impacts on the project area and its environ. The most important impact likely to take place will be the instability of SSCP canals and the channels by susidence, erosion and collapse of canal mouths, collapse of canal walls inducing large volume of sediments to move and block sea passages as well as submarine land slides leading to local Tsunamis

8. We have suggested in our reports, the necessity for carrying out various types of detailed remote sensing studies using satellite imaginaries of different band widths and wave lengths including Thermal Infra- Red imaginaries as well as different modeling studies on various aspects.

9. We have recommended the constitution of a Multidisciplinary Scientific Expert Committee to review all aspects of SSCP in a holistic fashion and suggest suitable types of further studies and their quantum.

10. On the status of Rama Sethu in our second report we have stressed that no detailed holistic scientific study on Rama Sethu has been done so far by any competent agency. Whatever has been stated on the Rama Sethu are based on spill over data from investigations that had different objectives. The important question should be not on the status of Rama Sethu physical feature, but whether any temporary bridge structure ever existed over it or any remnant of such bridge structure is existing on it at present. So far no detailed study with this objective has been carried out. We have recommended such a Marine Geo- archeological studies on Rama Sethu for this purpose.

11. The report of CEP states that the corals found on the Adams Bridge are in-situ biogenic coral reefs. on page 42. However this has been negated and contradicted in the report itself (vide pare 5.3.2 (ii) on page 49), where it is stated that the corals where uprooted, fragmented during cyclonic storms and deposited over the tectonic platform of Adams Bridge.

12. In the report of CEP vide pare 5.3, it is mentioned in all the bore holes, the coral occur in different depths and that there is no uniformity and continuity in the vertical and horizontal prevalence in the occurrence of coral, and that it is a clear cut natural stratigraphic cycle of sedimentation process. It is not a man-made feature. This nature of occurrence of coral, not extending at the same level in the adjoining bore hole, will indicate that it ends between bore holes which will probably means that it is a boulder like formation. The other statement in the report that the presence of coral and sand layers towards the top over a silty clay sequence cannot be regarded as a man-made layer serving as a cause-way bridge can also be interpreted as a simple road construction engineering phenomena. It is common practice that during road construction that repeated layers of boulders alternating with soil will be put to get proper compaction, and the behavior in bore holes noticed on Adams Bridge is very much akin to road construction.

13. In the report of CEP, the figure 5.1 on page 46 shows reconstructed natural depositional events in Adams Bridge area. It shows the bore hole log of BH5 of NIOT, and attributes different specific marine and current energy conditions for the formation of various layers within the vertical column. Coral formation is attributed to high energy shallow marine storm conditions. Similar condition should exit for the deposition of similar formations in adjoining boreholes also. As it is already been stated that corals do not extend at the same level to adjoining bore holes, if the above energy criteria is invoked, it will point to sudden change in the marine current energy conditions within short distance between two bore holes. This cannot happen in nature. Therefore it could only be inferred that the rocks, coral and any other occurring in the same level in two adjoining bore holes can only be different rock boulders which are earlier formed under different marine conditions and are placed at the same level by extraneous forces.

14. Para 5.4 of CEP report states that the opening of Sethu Samudram Channel will not have any impact due to cyclonic storms and Tsunamis on this fragile ecosystem. This is an erroneous conclusion. It is shown in the report of CEP that sediment influxes in large quantities are taking place even during normal times from the Bay of Bengal to Palk Bay. Palk Bay is already a shallow sea with highly turbid water. On the other hand Gulf of Mannar is a deep sea with clear water. At present, Adams Bridge / Rama Sethu acts as a barrier /check-dam preventing the sedments ladden turbid waters to flow from Palk Bay to Gulf of Mannar. If SSCP canal is cut across Adams Bridge, the turbid waters along with sediments will flow with high velocity and force through this narrow channel during Tsunamis and cyclones and fall into the Gulf of Mannar. The Gulf of Mannar side has a steep slope and this sediment-ladden water will fall like a waterfall creating further turbulence, and affect the tranquil nature of Gulf of Mannar waters, which will lead to disturbances in the fragile eco-system prevailing there.

15. Under para 5.4.3 and 5.4.4 it is stated that the future Tsunami waves also will travel towards the Indian coast only in East-West direction. The North-South trending SSCP Canal will actually reduce the wave energy. This is again a false statement as the SSCP Canal on the northern side cutting the Palk Strait is oriented along ENE – WSW direction and not along North-South. As such the future Tsunami waves even if they travel only in westward direction, this channel will act as a narrow tunnel to push the waves to cause heavy destructions.

16. Under para 5.4.5, the CEP report says the opening of the channel of SSCP will not play any role in increasing or decreasing the placer deposits of monazite, ilmenite, garnet, etc in the southern Tamilnadu and Kerala and that such minerals are already occurring in enormous amounts in other parts of our country. The above statements are highly inaccurate. No placer mineral deposit having monazite, ilmenite, etc of such large reserves and high grade occur in any other part of India.

17. It is to be noted that the above minerals are called heavy minerals because of their higher specific gravity. These minerals having been brought to the ocean along with sand and other mineral grains need particular type of current energy to jig, separate and concentrate them. The currents also need a specific orientation and direction for transporting such material to our coast. It has already been pointed out in the previous paras that opening up of SSCP Canal across Adams Bridge will induce large volume of turbid water of Palk Bay to fall into Gulf of Mannar with great force disturbing its tranquility. Such a disturbance will certainly reduce the current energies and their orientations. As a consequence there may not be much concentration of the heavy mineral or deposition of the same on our coast.

18. During the last Tsunami it was observed that the Tsunami waves after hitting the coast moved considerable distances on the land and later withdrew with force dragging lot of material back into the ocean. If large future Tsunamis which are likely to come through SSCP Canals into Gulf of Mannar attack the coast with added force, it is likely that they can drag the already existing heavy mineral deposits back into the ocean. This probability cannot be ruled out since incursions and withdrawal of sea are taking place along Tamil Nadu Coast regularly nowadays and detailed modeling studies with different wave energy patterns, varying amounts of heavy minerals and different orientation directions are necessary coupled with detailed Tsunami modeling studies in this area.

19. The CEP reports attempts at proving that Rama Sethu / Adam's bridge is formed by natural sedimentation process only and it is not a man made structure. However, as has been stated earlier no holistic scientific studies on Rama Sethu are conducted with a clear objective to find whether any temporary cause-way cum bridge existed there or any part of it is existing at present on the structure.

In our studies regarding the scientific status of Rama Sethu the following geographical signatures are noticed.


· It rises as a Very Steep Wall-like Feature from the Gulf of Mannar
· It is a "Strait" joining two seas-Palk Bay and Gulf of Mannar
· It is an "Isthmus" connecting two land masses – Rameswaram and Thalai Mannar islands under the sea.
· It is a unique curvilinear feature.
· It is nearly 17 Lakhs year old.
· It is a "Barrier Zone" that separates two contrasting seas- the shallow and turbid waters of Palk Bay from the deep and clear waters of Gulf of Mannar.
· It is a "Barrier / Protection Zone" against "Tsunami" impacts.


Due to theses reasons themselves, Rama Sethu can be declared as an "International Geographical Heritage Site" and protected.

20. Our studies also brought to light the accuracy and authenticity of Valmiki Ramayana in terms of Geographical and certain distinct Geological aspects.

The veracity of this historical narration is evident in Valmiki's references to a number of places and natural features in the country such as rivers, hills, etc., are still extant especially in southern parts of Tamil Nadu. The references to "Ayamukha Paravatha from which the placid waters of Kaveri are seen" indicating the iron ore bearing Kanjamalai hills, south of Salem is so accurate in terms of Geography and Geology Similarly, the locales and descriptions of Agasthiyamalai, Thambrparani river, the rising Mahendra Giri Hill, Rameswaram and Gandahamana Paravatha are described in detail very accurately.
Valmiki's descriptions of sea waves lashing against the foot hills of Mahendra Giri is supported by the reported occurrence of marine, fossiliferrous limestone in this area. It is to be noted that Mahendra Giri is at present far inland to the north of Nagercoil. Another interesting geological phenomena was described in the yuddha kanda of Valmikl Ramayana. When Rama requested the lord of sea to give way for his army to cross over to Srilanka and when the lord of sea did not appear in front of Sri Rama, Valimiki decribes that Sri Rama sent powerful arrows into the ocean. The entire earth trembled and large waves erupted followed by high heat and fire. It is very significant that this area is prone to earth quakes, high tidal waves and tsunami, and buried volcanoes. Valmiki also describes about certain floating stones that have been used for the construction of Rama's bridge. In nature, two such stones namely, pumice (a volcanic rock) and non-silicifide coral rock will float in water. These rocks occur in the Adam's Bridge and Gulf of Mannar areas All these geographical, geological features and phenomena cannot have come from the wild imagination of a poet sitting thousands of miles away in Ayodhiya. It is therefore, very clear that Ramayana is certainly a historical document supported by scientifical evidences

21. Astronomical evidences brought out recently by Pushkar Bhatnagar (Era of Rama, Ruba &CO, New Delhi) indicate that the age of Rama is around 7000 Before Present (BP). It is well known scientific fact that specific planetary positions will not repeat in millions of years. Using the planetorium software of NASA, Pushkar Bhatnagar recalibrated and recalculated the planetary positions described in Valmiki Ramayana during different events in Rama's life, such as Rama's birthday, the day before Rama's initial Pattabhishegam, the killing of demons Kara–Dhushan, killing of Vali, meeting of Hanuman and Sita at Srilanka etc., the last three being eclipses. These determinations coincide very accurately with the periods of events described in Ramayana.

22. Our report on Rama Sethu also interprets the following from the bore hole data of NIOT. Below a zone of loose marine sand upto 7 to 9 m depth, a zone of boulders made up of calcareous sandstone and coral inter-layered with silt and sand is encountered between 9 to 20 m. Below 20 to
22 m another marine loose sand is encountered. Similar geological setup is also reported from certain publications on the Thalai Mannar side of Srilanka. Such type of boulder beds between loose sand layers cannot be formed either by natural marine processes or by river processes along the sea coast. As such these beds should be a man-made structure only.

23. To confirm such an interpretation, we have suggestedgeo-archaeological studies on the Rama Sethu / Adam's bridge by large scale and deep pitting upto 25 m depth till the second loose sand zone is reached. Under-water video graphy and sampling of the four walls and the bottom at 50 cm interval for finding the composition, nature and age of the different formations are suggested. This will clearly establish the true nature of the Rama's bridge.



2 comments:

Gopi said...

Just to want to get to your notice. The yuga calculation seems much closer of how you have derived. (though i dont understand fully)

https://youtu.be/Do3HVreruO4

Regards

Gopi

Jayasree Saranathan said...

Thanks for bringing to my notice. The equinox part is challenge-able, so also the 'evidences' on summer solstice stars. In my article above, the classification of Yugas has no authentication, as I have mentioned. The classification in the video too has no authentic source. By this I mean these ideas cannot last.

Fortunately I happened to come across an authentication from Cholan inscription which I have reproduced in this article https://jayasreesaranathan.blogspot.com/2018/01/divya-and-dharma-two-sides-of-yuga_21.html By this we can say that the classification is applicable starting from Holocene. But then there is no way to quantify each yuga.

I have come a long way from my above article and in my current understanding, Dharma was applied as scale to measure the yugas mentioned for Rama and Krishna. There is no reversal from Kali to Satya. After Kali, Satya Yuga only starts.

Given the links to other parts in the same link where I have written on these. Alternatively you can download as a single paper from here

https://www.academia.edu/36652239/Yuga_classification_-_how_Yuga_must_be_understood