In educational settings, students are commonly taught that Earth comprises seven continents: Europe, Asia (which is often referred to as Eurasia when Europe and Asia are considered together), Africa, North America, South America, Australia, and Antarctica. Nevertheless, these are not the only landmasses that have existed since the planet’s formation.
Recently, there has been recognition of an eighth continent called Zealandia, which is predominantly submerged under water. Although it remains hidden from the Earth’s surface, modern satellites possess the capability to detect it. After remaining concealed underwater near New Zealand for numerous years, geologists officially confirmed the existence of this enigmatic new continent in early 2017.
Uncovering the Submerged Continent of Zealandia
The discoveries made about this submerged continent were truly fascinating. Among the intriguing clues were the presence of continental rocks in unexpected locations and gravity anomalies surrounding a vast underwater area. Every continent on Earth is supported by massive sections of rock known as tectonic plates, buried beneath the surface. Over the course of the Earth’s 4.5 billion-year history, the movement of these plates has profoundly altered the positions and shapes of all the continents. As a result, continents like Zealandia have gradually submerged under water due to these ongoing tectonic activities. It’s remarkable to consider that our planet is, in essence, a dynamic and ever-changing entity, continuously shaped by these tectonic movements.
Geologists have recently disclosed that the highest points of the long-lost continent Zealandia are the elevations of New Zealand and New Caledonia in the South Pacific. Countless years of slow continental movements have caused the majority of Zealandia to become submerged underwater. Until the 20th century, the existence of Zealandia remained unknown to the world. The revelation of this hidden continent has opened up new frontiers in our understanding of the Earth’s geological history.
History of Zealandia
In addition to being a mysterious and submerged continent, Zealandia, also sometimes referred to as Tasmantis, has some other known characteristics. This lost continent was formed in a very early period of Earth’s history, about 600 million years ago, and was once part of the vast supercontinent called Gondwana.
During Earth’s early history, the continents were one large, cohesive landmass, but as tectonics continued their slow movements, these landmasses drifted apart. Zealandia, carried by tectonic plates itself, merged with another primitive continent called “Laurasia” to form the supercontinent known as “Pangaea.” However, the fate of Zealandia was sealed underwater by two tectonic plates beneath it, namely the southern Pacific Plate and its northern neighbor, the Indo-Australian Plate. These plates were moving apart from each other by a few millimeters every year, and about 85 million years ago, they gradually separated Zealandia from Antarctica and Australia. This gradual drifting caused Zealandia to sink, and during the Late Cretaceous Period (around 66 million years ago), most of the continent became submerged. Only New Zealand, New Caledonia, and some smaller islands remained above sea level.
Geology of Zealandia
The ongoing movements of tectonic plates beneath Zealandia’s submerged region continue to shape the underwater geology, giving rise to geological formations known as grabens and basins. Additionally, areas where one tectonic plate is being subducted beneath another experience volcanic activity. The compression of plates in certain zones leads to uplifting movements, which have resulted in the formation of prominent features like the Southern Alps. This process can be compared to the formation of the Himalayas, which occurred when the Indian Peninsula collided with the Eurasian plate.
The oldest rocks identified in Zealandia date back to the Middle Cambrian period, approximately 500 million years ago. These rocks predominantly consist of limestone and sedimentary rocks with abundant marine organism shells and skeletons. There are also granites, which are volcanic rocks composed of minerals like feldspar and biotite dating back to the same era. Geologists are actively studying core samples from Zealandia and comparing its rock formations with those of Antarctica and Australia, which are believed to have once been part of Zealandia’s ancient neighbors. The ancient rocks uncovered so far provide valuable evidence of the rifting movement that eventually led to the submersion of Zealandia millions of years ago. Similar to volcanic rocks and other geological features found in islands and above-water continental areas, comparable features are evident in Zealandia, further supporting its continental nature.
How Was Zealandia Discovered?
The unearthing of Zealandia presents a perplexing geological enigma that gradually unravels through persistent investigation. As early as the 20th century, scientists were cognizant of submerged territories in the vicinity. Nevertheless, it was only approximately two decades ago that the notion of it constituting a concealed continent took root. Through meticulous scrutiny of the oceanic floor in the area, it became evident that the crust beneath it deviated from the characteristics of standard oceanic crust. The rocks extracted from the ocean floor and samples from its depths diverged markedly from the typical composition of oceanic crust, resembling instead a continental rock type. It is essential to underscore that such an extraordinary revelation would not have been attainable without the presence of an obscured continent beneath the aquatic realm.
Consequently, in 2002, satellite measurements facilitated the creation of a gravity map of the region, thereby delineating an initial approximation of the continent’s configuration. Because the oceanic crust and continental crust have different gravitational properties, which can be seen with satellite instruments, there is a clear line between the deep ocean floor and the Zealandia region. This makes geologists more sure that this lost continent does exist. With the subsequent accumulation of rock core data, underwater exploration by marine geologists, and comprehensive satellite cartography, geologists were ultimately persuaded of Zealandia’s verifiable continental identity. The culmination of decades of painstaking research culminated in the official proclamation of Zealandia as a bona fide continent in 2017 by the esteemed geological team.
Why Zealandia Matters?
Presented in the image is a cartographic representation of Zealandia, an expansive continent covering an area of approximately 1,930,511 square miles, with only a limited portion visibly exposed above sea level. The cartographic depiction employs a color-coded scheme, wherein continental crust is distinguished by a range of warm tones such as red, orange, yellow, and brown, while oceanic crust is elegantly denoted in varying shades of blue. Additionally, volcanic island arc crust is depicted in a delicate pink hue, whereas large igneous provinces are identified through the use of a lush green shade.
Abundant in valuable natural resources, Zealandia has garnered significant attention from international governments and corporations alike. Nevertheless, beyond its economic significance, the continent boasts active mineral deposits and hosts distinctive ecosystems that persistently flourish. Geologists and planetary scientists assert that this region bears immense potential for unraveling Earth’s extensive historical timeline spanning millions of years. Moreover, its geological characteristics might provide invaluable insights into landforms observed on celestial bodies within our Solar System. Zealandia, therefore, serves as an exceptional locale for scientific exploration and discovery, encompassing both terrestrial and cosmic perspectives.
- Uruski, Christopher I. (2010). “New Zealand’s deepwater frontier”. Marine and Petroleum Geology. 27 (9): 2005–2026.
- Yarwood, V. (November–December 2014). “Zealandia: Our continent revealed”. New Zealand Geographic. Book Review.
- Gorvett, Zaria (8 February 2021). “The missing continent it took 375 years to find”. BBC.