Isla Nublar era sempre vulcânica, ou era um retcon?

O primeiro rascunho do roteiro para o primeiro filme contém uma linha de Hammond descrevendo a ilha explicitamente como um vulcão extinto (embora esta linha esteja ausente do versão final do script):

Isla Nublar. Actually an extinct volcano, though there's still volcanic steam in places... as you can see, ocean currents make it permanently covered in mist.

A linha acima é uma paráfrase de uma citação do livro original, que freqüentemente ¹ menciona a atividade vulcânica da ilha. De fato, o próprio nome da ilha deriva disso:

Isla Nublar, Hammond explained, was not a true island. Rather, it was a seamount, a volcanic upthrusting of rock from the ocean floor. "It's volcanic origins can be seen all over the island," Hammond said. "There are steam vents in many places, and the ground is often hot underfoot. Because of this, and also because of prevailing currents, Isla Nublar lies in a foggy area."

Por que a InGen construiria um parque em uma ilha que tem um vulcão?

Podemos supor que isso ocorre porque os criadores do parque supuseram que um ambiente diverso e vulcânico seria mais "natural" para os animais, ou que seria propício para a preservação de várias espécies variadas:

It was during the early Triassic period that Procompsognathus had lived... The air was denser. The land was warmer. There were hundreds of active volcanoes. And it was in this environment that Procompsognathus lived.

... when Grant looked at this landscape, he saw... another, very different world, which had vanished eighty million years ago... At that time, there were thin clouds in the sky overhead, darkened by the smoke of nearby volcanoes. The atmosphere was denser, richer in carbon dioxide.

Costa Rica had a remarkable diversity of biological habitats: seacoasts on both the Atlantic and the Pacific; four separate mountain ranges, including twelve-thousand-foot peaks and active volcanoes; rain forests, cloud forests, temperate zones, swampy marshes, and arid deserts. Such ecological diversity sustained an astonishing diversity of plant and animal life. Costa Rica had three times as many species of birds as all of North America. More than a thousand species of orchids. More than five thousand species of insects.

Fontes

^{1. Jurassic Park , Michael Crichton}

^{Along the side of the road, clouds of volcanic steam misted rainbows in the bright quartz lights... Land Cruisers moving through fields of steam... The southern end of the island had more volcanic activity than the north.}

^{He smelled the sulfur fumes of the volcanic steam... Already he could smell the sulfur. And up ahead he saw the rising steam of the volcanic fields.
The ground was hot, Gennaro thought, as he walked forward. It was actually hot. And here and there mud bubbled and spat up from the ground. And the reeking, sulfurous steam hissed in great shoulder-high plumes. He felt as if he were walking through hell... They all walked forward, among the bubbling steam vents.}

^{"The raptors are localized in the southern area, down where the volcanic steam fields are. Maybe they like the warmth."... It looked more and more as if Ellie had been correct: the nest was in the southern volcanic fields.}