Many ancient cultures believed that the Earth, heavens, animals and mankind were originally created just as they are now, remaining unchanged until today. Even as many of these notions were slowly eroded by more logical scientific arguments, the belief that the ancient Earth was created at its present size persisted, until it became a major world paradigm even within science.
Today students are still taught that the Earth was created over 3.8 billion years ago at its present size, maintaining this same diameter until today, but modern geological evidence seems to demonstrate this concept of a Constant Diameter Earth may be completely wrong.
Other thoughts about the Earth have changed dramatically. By the end of the 19th century the most widely held geological model was that the Earth was slowly cooling, thereby causing the Earth to shrink slightly to form mountains as the surface wrinkled. In the early 1900s the continents were still considered to have been firmly fixed in place since the beginning of the Earth but in 1912 the German meteorologist Alfred Wegener proposed that the continents had once been joined in one gigantic land mass and then drifted apart to finally end up in their present positions. In 1915 he presented this evidence in the first edition of his book, The Origin of Continents and Oceans (Die Entstehung der Kontinente und Ozeane). Most scientists of the day disagreed and it was dismissed as ‘an absurd daydream’. Other people noted that Francis Bacon, Snider-Pellegrini, Frank Taylor, Howard Baker and Roberto Mantovani had also noted that coastlines fitted together. This coastal fit was one of the strongest lines of evidence for Continental Drift, but Wegner also matched fossils and geology across widely separated continents as further evidence.
By the 1930s most scientific opinion was firmly against Continent Drift although there were still some notable individual supporters. The South African geologist, Alexander du Toit published some of the best arguments in support of it in his 1937 book Our Wandering Continents. The British geologist Arthur Holmes also championed the theory of Continental Drift while it was still unpopular and his book Principles of Physical Geology ended with a complete chapter on Continental Drift.
One major supporter of Continental Drift at this time was the Australian geologist S. Warren Carey who organized a number of international conferences on Continental Drift and taught the subject in his classes.  In 1956, while reconstructing the continents on a large 76 cm diameter globe, he noted that the fits were not perfect on an Earth of the present diameter, but if a smaller diameter Earth was used then the fit was perfect. He considered this for two years and then finally publicly announced in 1958 that he believed Continental Drift had been caused by the Earth expanding in size. But for most people accepting the Earth had expanded was difficult to believe.
Carey ‘discovered’ the concept of expansion completely independently of any previous thoughts on the subject but his further research showed that a number of people had published similar proposals in the past. In 1933, one explanation for continental drift had been proposed by Ott Christoph Hilgenberg in his book, Von wachsenden Erdball, which roughly translates as ‘The Expanding Earth’. He observed that all the continents could be reconstructed on a smaller diameter Earth and suggested that the Earth had expanded in size to split the continental shell into the various continents of today, until they eventually reached their present positions. Also the Russian engineer Jean Yarkovsky and the Italian geologist Roberto Mantovani had both independently suggested the concept towards the beginning of the 1900s. But these ideas had been mostly ignored during their day since most people believed the continents were firmly fixed throughout geological time.
During the mid-1950s the ocean floor began to be studied with echo sounding equipment and this eventually resulted in the first map of the ocean floor being published in 1959 by the American geologists Bruce Heezen, Marie Tharp and Maurice Ewing. The map was a revelation because it showed details that had never been seen before (one of these original maps of the ocean floor is available on Google Earth as shown below).