# Was volcanic activity more prevalent when the dinosaurs roamed?

Popular film culture often depicts much volcanic activity during the time of the dinosaurs.

Assuming "time of the dinosaurs" as the Jurassic (200 million years ago) until the end of the Cretaceous (66 million years ago):

Are there any geological theories that support such an assumption?

• Good question, come to think of it - volcanism always seems to be a prevalent sub-theme in movies like this. – user889 Dec 10 '14 at 4:52
• This is spanning almost 150 million years. I'm confident that both active and quiescent times existed. It also depends on your location. Even today, someone living in Kamchatka may have a different idea about contemporary volcanic activity levels than someone living in London. Since actual volcanic activity today occurs in very specific locations, marked by hotspots and subduction zones, I assume this was similar back then as well. – Gimelist Dec 10 '14 at 6:32
• However, since the interior of the Earth was slightly hotter 200 million years ago, it could be that overall volcanic activity levels were slightly higher than they are today. Nonetheless, the common depiction of volcanoes with dinosaurs is mostly done for artistic reasons I believe. – Gimelist Dec 10 '14 at 6:36

There seems to be indeed reasons to believe in an enhanced volcanism during the Cretaceous at least.

The Cretaceous timescale is indeed peppered by the formation of large igneous provinces (known collectively as LIP; short review in Ogg & Hinnov 2012a): Parana at ca. 135Ma, the Ontong-Java Plateau at ca. 125Ma, the Kerguelen Plateau at 118Ma, the Caribbean Province at 90Ma and of course the famous Deccan Traps at the K/Pg boundary. In addition to those large events, they were as well other more minor pulses of large-scale volcanism during the earliest Cretaceous (Shatsky Rise), and at ca. 87Ma (Madagascar Traps) and ca. 73Ma (Sierra Leone Rise).

The 5 LIP, though localized to a specific region each time, had a global impact on the climate and on the oceans, as seen on $\delta ^{13}C$ curves for instance, or during the different episodes of Oceanic Anoxic Events.

As far as the pop culture trope is concerned, most of these volcanic events were partly underwater (Shatsky Rise, Sierra Leone Rise, Kerguelen Plateau, Ontong-Java) so I doubt dinosaurs were roaming around active volcanoes. It is probable that the trope originated instead in the idea that the Deccan Traps triggered the end Cretaceous mass extinction (i. e. the disparition of non-avian dinosaurs, in particular).

In comparison (see Ogg & Hinnov 2012b), there were only one LIP forming during the Jurassic in the Karoo Basin (South Africa); if we ignore the Central Atlantic Magmatic Province which formed just below the base of the Jurassic (it may or may not have caused the end-triassic mass extinction).

Ogg, J. G. & L. A. Hinnov, 2012a. Cretaceous. In F. Gradstein et al (Eds), The Geologic Time Scale 2012, Elsevier, Amsterdam: 793-853.
Ogg, J. G. & L. A. Hinnov, 2012b. Jurassic. In F. Gradstein et al (Eds), The Geologic Time Scale 2012, Elsevier, Amsterdam: 731-791.