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The Holocene Epoch is the current period of geologic time. It relates to the global changes caused by human activity, and is said to have begun about 11.700 years ago after the icy Pleistocene ended. When the glaciers of the ice era retreated, Earth entered a period of warming. The landscape of the tundra changed, large mammals that had adapted to the extreme cold became extinct, and humans who hunted the mammoth mammals began exploring plant materials to supplement their diet. Climatic changes took place, the human population began to grow, and sadly, we began ushering in processes and inventions that would have serious implications on the future of the planet.

The classification of the geological time scale is done into the following: Eons, Eras, Periods, Epochs and Ages. In this timeline classification, Eons are divided into Eras, Eras are further divided into Periods, Periods divided into Epochs and the Epochs are further subdivided into Ages. Thus, Holocene is an Epoch classified under the Quaternary Period, which comes under the Cenozoic Era, which is classified under the Phanerozoic Eon.

Under the classification of the Quaternary Period, comes the Pleistocene Epoch and Holocene Epoch. The Holocene is the Epoch which follows the Plestocene Epoch. It is also identified as a warm period and an interglacial period by the geologists, and Earth scientists. The striking feature of the Holocene time scale is the rapid proliferation, growth, and the impacts of Human species. The Holocene is characterized by all of the written history, technological advancements, development of many civilizations, and the current transition towards urbanization of the human population. The influence of humans is predominant in this Epoch and the impact on modern-era Earth and the ecosystems have led to the classification of the Holocene. 

The Holocene Time-scale

The word Holocene finds its origin in the Ancient Greek language. Holocene meaning, according to Ancient Greek, is “whole new”. Breaking the word of Holocene into the Greek roots helps in identifying the holocene meaning. The term ‘Holo-’ is derived from the word Holos which means “whole”. The other ‘-cene’ is derived from the word kainos which means “new”.Thus, when combined together, the holocene meaning is “whole new”. The reasoning behind this, is the consideration that this epoch is entirely new as it is the most recent one and is still continuing. Also, the suffix ‘-cene’ is used for all the seven epochs that are classified under the Cenozoic Era. 

According to the International Commision on Stratigraphy, the Holocene started 11,650 calibrated years ago before present. The Holocene Epoch is further sub-divided into five time intervals based on climatic fluctuations, which are also known as the Chronozones:

Preboreal: This is the time period between 10 kiloannum (ka) years - 9 ka before present (BP) (present i.e. 195)). 
Boreal: This lies between 9 ka - 8 ka years BP
Atlantic: 8 ka to 5 ka years BP
Subboreal: 5 ka - 2.5 ka years BP
Subatlantic: 2.5 ka years BP.

During the time of the Holocene, there have been many changes that have taken place in terms of geology and climate which have shaped the current world. Also, the changes occurring due to Global warming in the last century itself has also impacted the natural progression of this Epoch. We will understand a few of these changes as we go through with the article.

Geological Changes During Holocene

The movements of the continent under the pressure of tectonic forces, has been less than a kilometre in the span of 10,000 years of Holocene. Another important change in the geology of the Earth, during this Epoch has been the rise in the sea-level. In the early part of the Holocene Epoch, because of the melting of ice, the sea-level rises about 35 m. In the later part of the Epoch also, the sea-level rises by another 30 m. Many of the areas of landmass above around 40 degrees North latitude that had been covered by ice of the Pleistocene Epoch were depressed by the weight of Ice. Hence, as the glacial period began to recede and the ice began to melt, the landmass rose by180 meters during the late Pleistocene and early Holocene Epoch. These landmasses still continue to rise. 

Climate Changes During Holocene

As such the climate changes have been stable over the Holocene when compared to the cold period of Glaciation. The records collected from the ice cores have shown that before the start of Holocene there was a time period of warming happening globally which began after the end of the last of the ice ages and the cooling periods. The climatic changes became more and more regional and during the transition from the late glacial to Holocene the cold reversal known as Huelmo-Mascardi, began from South America in the Southern Hemisphere and most of the warmth flowed from south to north about 11,000 to 7,000 years ago. It is thought that this happened because of the residual glacial ice which was left in the Northern Hemisphere.

Early Human Settlements During Holocene

The Mesolithic age began with the beginning of the Holocene in most of Europe. In the regions of Middle East and Anatolia a very early neolithisation and Epipaleolithic period began. During this period the cultures that began include Hamburgian, Federmesser and Natufian culture. Also, some of the oldest inhabited places that are still existing such as the Tell es-Sultan (Jericho) in the Middle East began to be first settled. Other evidence of such settlements are given by archaeology at locations of Göbekli Tepe where proto-religion first began as long as 9th millennium BCE. Since then human courses have taken the known developments and continue till date.

It is noteworthy that, using terms like Holocene period, Holocene era or Holocene age, can be confusing as the terms period, era and age have different and definite meaning under the Geographical Time Scale classification system Hence, using Holocene or Holocene Epoch is more reliable and justifiable under such circumstances. 

Credit : Vedantu learn live 

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Among bird-like dinosaurs such as the Troodon, Oviraptor and the Citipati, it was the male which guarded the nest and brood. This came to light when scientists who studied the fossil remains of these dinos found the males with large clutches of eggs.

For the new research, paleontologist David Varricchio of Montana State University in Bozeman compared three species of birdlike dinosaurs--Oviraptor, Citipati, and Troodon--with birds and crocodiles. All three types of dinosaurs were found on nests, and those nests contain large clutches of eggs, as many as 30 each. Varricchio and his colleagues investigated whether they could discern the nesting behavior from the relationship of the clutch size and the animal's body size. Measurements in 433 living birds and crocodiles revealed that, for a given body size, species in which males took care of the nest tended to have the largest clutches. The next-largest clutches were cared for by mothers. Mom-dad partnerships had the smallest clutches. Extrapolated to dinosaurs, the data revealed a pattern of paternal care in the ancient beasts.

Another line of evidence in the paper comes from Gregory Erickson, a biologist at Florida State University in Tallahassee. His studies of dinosaur bone tissue showed that none of the seven specimens associated with nests showed signs of changes associated with egg laying, such as medullary tissue . That's not sure-fire proof the nest-caretakers were male, he notes, but it's consistent with the hypothesis. The findings are reported in tomorrow's issue of Science.

Richard Prum, an ornithologist at Yale University, says he never expected paternal care in dinosaurs. But with their dinosaur ancestors showing more and more traits once thought to be exclusive to birds, such as feathers, he says the finding makes sense. It also points to a question on the reproductive frontier: Did dinosaurs practice polygamy?

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The Yellow Brick Road in L Frank Baum's The Wonderful Wizard of Oz is in the spotlight after a bunch of marine researchers recently stumbled upon a "strange yellow brick road" in the bottom of the Pacific ocean.

How did L Frank Baum think of a Yellow Brick Road?

Dorothy and her dog are whisked away from Kansas into the strange world of Oz by a tomado. They meet a Witch of the North, who tells them that they have to go through a Yellow Brick Road that leads to the Emerald City to find the Wizard of Oz who would help them find their way back. What ensues is an adventurous journey through the yellow brick road, along which they meet a talking Scarecrow, a Tin Man and a cowardly lion, who become their friends. The yellow brick road, however, was far from smooth. It was broken in places, with deep chasms leading to steep cliffs.

L. Frank Baum, the author of The Wonderful Wizard of Oz is believed to have been inspired by a brick road in Peekskill, New York, where he attended the Military Academy. However. Roger S Baum, the great grandson of Frank Baum and a children's book author, says the yellow brick road in the books was actually inspired by the winding cobblestone roads in Holland, Michigan, where Baum loved to spend summers with his family.

There is another claim, which states that Baum once stayed in a hotel in Dallas, Texas, during his newspaper career. This was a time when the streets were paved with wooden blocks of Bois D'Arc also known as Osage Orange. It is said that when Baum looked out of the window of his room after a rainstorm, when the sun was just coming out, he saw a bright yellow brick road, which made way to his book.

The yellow brick road appears not just in the first book of the Oz series, but in their sequels, too-The Marvellous Land of Oz (1904) and the Patchwork Girl of Oz (1913).

There were several roads nearby, but it did not take Dorothy long to find the one paved bricks" with yellow

 

The central character in the 1900 children's classic The Wonderful Wizard of Oz took this road, her silver shoes making a tinkling sound on the hard yellow road-bed. This golden thoroughfare would lead her to Emerald City, located in the exact centre of the continent

Bizarre, but true

Looks like a team of researchers felt like Dorothy when they stumbled upon what looked like a yellow brick road at the bottom of the ocean. Recently, a little north off the islands of Hawaii, a marine exploration vessel Nautilus found a strange "yellow brick road" on the bed of the Pacific ocean.

While studying an area called the Liliuokalani Ridge in the Papahanamokuakea Marine National Monument, the researchers say they found what looked like an ancient dried out lake bed paved with yellow bricks. Though underwater, the "yellow brick road" appeared dry, "almost like a baked crust of earth that could be peeled off.”

The team found the formation bizarre. One of them quipped that this could be Dorothy's yellow brick road, while another wondered if this was the road to Atlantis, a fictional island that appears in ancient Greek philosopher Plato's works.

 The road on the seabed could be the result of fractures in a volcanic rock that gives it the appearance of a bricks, says the team.

Oz worlds

The US has a number of Oz-themed parks, where one can join Dorothy on her adventurous trip to Emerald City. Some of these parks have created yellow brick roads too.

Liberal in Kansas, United States of America, has a 'Dorothy's House', 'Land of Oz and the 'Coronado Museum', which pay tribute to the characters in The Wizard of Oz. There is an Oz-themed park here as well.

Aberdeen in South Dakota, the US, has Storybook Land' and the Land of Oz Atractions based on the adventures of Dorothy.

The Land of Oz located in Beech Mountain, North Carolina, is a theme park based on Baum's Oz books. It was opened in 1970 and was fully operational until its closure in 1980. Now, it has reopened with Journey with Dorothy' tours and Autumn at Oz festivals.

Picture Credit : Google