Sunken landmasses in the Indian Ocean

[baggins15]

Basically working on an ATL project involving a less boring Indian Ocean, as per my map above. What if some of these sunken landmasses such as Kerguelen, Broken Ridge and the Mascarene Plateau never disappeared beneath the waves, instead remaining above sea level following the Late Cretaceous/Holocene? Just after some input to help move things along as I'm a little stuck.

What flora and fauna could we see? Mammals such as lemurs probably make it to the Mascarene Islands I'd imagine, but might life in the more isolated lands like Kerguelen and Broken Ridge have evolved more along the lines of NZ (i.e. no native mammals and lots of flightless birds)? How about climate and possible impact on ocean currents?

As for humans, I'm assuming the larger Mascarene Islands are settled by Austronesians (as Madagascar was), even though they weren't in OTL. Thinking I can rule out a similar pre-European population in Kerguelen though, with Broken Ridge perhaps a more likely possibility? And how might things develop once Europeans arrive?

[lordroel]

Mar 19, 2023 11:25:28 GMT baggins15 said:

Basically working on an ATL project involving a less boring Indian Ocean, as per my map above. What if some of these sunken landmasses such as Kerguelen, Broken Ridge and the Mascarene Plateau never disappeared beneath the waves, instead remaining above sea level following the Late Cretaceous/Holocene? Just after some input to help move things along as I'm a little stuck.

What flora and fauna could we see? Mammals such as lemurs probably make it to the Mascarene Islands I'd imagine, but might life in the more isolated lands like Kerguelen and Broken Ridge have evolved more along the lines of NZ (i.e. no native mammals and lots of flightless birds)? How about climate and possible impact on ocean currents?

As for humans, I'm assuming the larger Mascarene Islands are settled by Austronesians (as Madagascar was), even though they weren't in OTL. Thinking I can rule out a similar pre-European population in Kerguelen though, with Broken Ridge perhaps a more likely possibility? And how might things develop once Europeans arrive?

First welcome aboard, second these lost land masses not disappearing would mean more territory i think for the British and the Netherlands.

[stevep]

Mar 19, 2023 11:32:58 GMT lordroel said:

Mar 19, 2023 11:25:28 GMT baggins15 said:

Basically working on an ATL project involving a less boring Indian Ocean, as per my map above. What if some of these sunken landmasses such as Kerguelen, Broken Ridge and the Mascarene Plateau never disappeared beneath the waves, instead remaining above sea level following the Late Cretaceous/Holocene? Just after some input to help move things along as I'm a little stuck.

What flora and fauna could we see? Mammals such as lemurs probably make it to the Mascarene Islands I'd imagine, but might life in the more isolated lands like Kerguelen and Broken Ridge have evolved more along the lines of NZ (i.e. no native mammals and lots of flightless birds)? How about climate and possible impact on ocean currents?

As for humans, I'm assuming the larger Mascarene Islands are settled by Austronesians (as Madagascar was), even though they weren't in OTL. Thinking I can rule out a similar pre-European population in Kerguelen though, with Broken Ridge perhaps a more likely possibility? And how might things develop once Europeans arrive?

First welcome aboard, second these lost land masses not disappearing would mean more territory i think for the British and the Netherlands.

  Also the French and possibly the Portuguese although how well the latter can hang onto them as their power declines would be an issue?

  I suspect that Kerguelen remains pretty unsettled as I think the climate there is pretty much sub-antarctic.  Possibly mainly say seals and the like with possibly some penguins making it that far north.  [They did reach the equator in the Pacific after all].  Might see a short period of economic activity with sealing and whaling although possibly also some more general fishing if the conditions are right.

  Not sure what happens with the Broken Ridge lands.  They could be discovered fairly late as I think most shipping went further north for a long time so possibly not until western Australia is settled.  Possibly someone like Captain Cook discovers it in the 18thC but might be too far north as I think his and other explorations in the region were further south probing for the believed southern counter-weight continent.  Not sure about settlement before the European era but possibly the island nearest Australia is the most likely to be discovered.

  The islands north and east of Madagascar are going to be discovered earlier of course and as with the other regions a lot will depend on their nature.  Is there suitable arable land or mineral resources?  Similarly possibly with fishing resources.  Is any of it volcanic, which could make for fertile soils but depending on how active the volcano/volcanoes are could make it a risky location.

  As you say what happens with currents, both sea and possibly also wind and the effects on climate in the region would be important both for them and wider afield but don't know anything like enough about the existing patterns in the region to guess how they might be affected.

[baggins15]

Mar 19, 2023 12:40:49 GMT stevep said:

  Also the French and possibly the Portuguese although how well the latter can hang onto them as their power declines would be an issue?

  I suspect that Kerguelen remains pretty unsettled as I think the climate there is pretty much sub-antarctic.  Possibly mainly say seals and the like with possibly some penguins making it that far north.  [They did reach the equator in the Pacific after all].  Might see a short period of economic activity with sealing and whaling although possibly also some more general fishing if the conditions are right.

  Not sure what happens with the Broken Ridge lands.  They could be discovered fairly late as I think most shipping went further north for a long time so possibly not until western Australia is settled.  Possibly someone like Captain Cook discovers it in the 18thC but might be too far north as I think his and other explorations in the region were further south probing for the believed southern counter-weight continent.  Not sure about settlement before the European era but possibly the island nearest Australia is the most likely to be discovered.

  The islands north and east of Madagascar are going to be discovered earlier of course and as with the other regions a lot will depend on their nature.  Is there suitable arable land or mineral resources?  Similarly possibly with fishing resources.  Is any of it volcanic, which could make for fertile soils but depending on how active the volcano/volcanoes are could make it a risky location.

  As you say what happens with currents, both sea and possibly also wind and the effects on climate in the region would be important both for them and wider afield but don't know anything like enough about the existing patterns in the region to guess how they might be affected.

The Dutch came across Australia's west coast during the 17th century and subsequently developed the Brouwer Route, so they're certain to have bumped into Broken Ridge too. I guess whether they colonise it remains up in the air though since they never bothered with nearby Western Australia. Thoughts?

What you said about Kerguelen seems on the money IMO, though I'm thinking that the east coast might have a milder climate due to it being sheltered from the prevailing westerly winds. The northern latitudes reach as far as the southern tip of NZ and so I suppose we could see some more substantial settlement in the north-eastern region. The rest would pretty much be a giant tundra though with the coast heavily indented by fjords. 

[baggins15]

Looking at the location of the Mascarene Islands, they're ultimately going to be claimed by Portugal. Just thought to myself that this could potentially butterfly their colonial presence throughout Asia and East Africa. With these islands, they're more likely to have held onto Ceylon and their possessions in India, and they probably become the first Europeans to claim the Maldives and Chagos Archipelago too. Wonder if this also means a stronger presence throughout SE Asia and Oman never being captured by the Ottomans? I doubt Portugal bother with the more southern islands though unless their discovery results in the Portuguese/Spanish developing the Brouwer Route before the Dutch (unlikely but an interesting hypothetical).

Also thinking that Kerguelen shifts the Antarctic Circumpolar Current south, possibly resulting in a warmer climate than I initially expected. The southerly latitudes will still border on tundra, but the north might be cloaked in temperate forests similar to those found throughout northern Patagonia, New Zealand and southern Australia. Don't know what impact this might have on Antarctica - perhaps a warming of the coastal areas? Even with this in mind, I'm still not sure the Malagasy or whoever settle here - after all, they didn't bother with warmer islands such as Mauritius and wouldn't be able to develop any sort of agriculture. Arab sailors might discover it during the Middle Ages but I doubt they'd have any reason to colonise it either. More likely, I think Abel Tasman stumbles across it in 1642 and finds an uninhabited land, perhaps with a few scattered artefacts indicating the presence of a failed earlier settlement.

As for Broken Ridge, it seems like it'd be on the very edge of where tropical crops might grow, but I think Austronesians could make things work if they landed there. The issue is discovering it in the first place though since ocean currents mostly lead away to the west, meaning sailors from SE Asia might not necessarily have an easy time getting there. In any case, the Dutch probably have first dibs on it, but like many of their other colonies I'd imagine it gets taken over by the British following the Napoleonic Wars.

[gillan1220]

This could be like the plot of King Kong where Skull Island exists in the middle of the ocean. Think of the amount of lost worlds these islands would be by the time of the age of exploration.