(Seamless? Not that you would guess from their juxtaposed continental margins.)
Fig.0. Madagascar to Africa fit. (a) Looks good to me. (b) Looks even better. [Added as an afterthought to the post below in case it wasn't clear what I meant by the juxtaposed continental margins looking a bit iffy.] Superficially the split looks good, as in (a), but when the geology is taken into acount the waterline itself won't do, .. because the build-up of stratigraphic sequence over time has to be taken into account (b); see Fig.4 below).
(... Still harping on about the importance of letting the data speak for itself, rather than being guided by theories), .. the fit of Madagascar to Africa provides us with a good case in point, .. because did it? I mean, fit? .. once upon a time?
This example illustrates the criticism that Wegener faced in relation to the Atlantic in a nutshell, but these days we are in a much more foward position to answer the question. Continental shapes are much more readily accepted as indicative of crustal rupture than in Wegener's day, and spreading ridges and transform faults are accepted too as indicative of the trace of continental separation. This adds much to the arsenal of 'facts' that that may be brought to bear on the question, .. the 'facts' are no longer 'hypotheses'.
Nevertheless, in regard to Madagascar and Africa (and India) and in a context of Plate Tectonics and Earth expansion there does remain some aspects of theory in regard to where Madagascar might once have fitted. Certainly Madagascar is a crustal fragment, and there are geological similarities with Africa (and India), .. biological similarites too, and clearly (given what we know of spreading ridges) the Indian ocean was once closed. So where precisely did Madagascar fit in the jigsaw puzzle?
Best Plate Tectonic practice using the objectified data of palaeomagnetism and the geophysical black box puts it in what is called the "northern position" (Fig.1), with consequences for the entire population of continents waiting to grow into so-called plates to the east and south in the figure,
Fig.1. Madagascar - Africa fit according to Plate Tectonics best practice can-o'-worms palaeomagnetism, in what is known as the 'northern position' (about 2,500km further north of the "southern position'). (Image courtesy of http://www.scotese.com/satlanim.htm .)
Fig.2. Alternative fits of Madagascar to Africa. 1. = Northern position (according to the 'objectified data of palaeomagnetism' and consensus Plate Tectonics); 2. = southern position ( according to the subjective, opinionated, non-scientific correlation of geology and Earth expansion here). (Click the image for a bigger figure; geology courtesy of UNESCO world map.)
See how 'science' is done? And why geology gets such a bad rap? You're supposed to distance yourself from the data, .. "objectify" it. Put it in the box, shake it, close your eyes, and Lo! the box will speak. Using your head (a.k.a. 'common sense) is not considered 'science'. You have to 'measure it' to make it 'science', then theorise what it means. That way you're ok, according to 'The Method'.
[ Bloody 'Method' actors, .. doing Plate Tectonics.. ]
Now, .. I would agree with that (about measuring being science). There's nothing scientific about common sense though. Common sense is the destination at which science hopes to arrive. Through the application of science, puzzles become common sense, self-evident truths. Commonsense transcends 'The Method'. And that's what geology boils down to with its commonsense ('Pssst') Principles of Stratigraphic and Structural Superposition shouting clues in our ear, by which commonsense application all is revealed, if we just keep our hypotheses and theories out of the way - Common Sense Rules.
So let's see how we get on with some anti-science commonsense (Fig.3).
Fig.3. Anti-science common sense revealed. The fit of Madagascar and Africa according to commonsense Geology and Earth expansion. Is seamless. The detachment from Africa, which is axial to the syncline (blue-and-green "boomerang'', bounded by blue) at the southern extremity of the Great African Rift Valley, is hardly detectable. (Blue = Jurassic, Green = Cretaceous; mixed sediments and volcanics) Geology courtesy of UNESCO.
It's obvious, .. it's where it all happened. No need for 'supporting' palaeomagnetics - which are not supporting at all. Just like day and night are perfectly explicable to our space traveller in terms of shadow cast by a spinning Earth, and an avalanche burying the village (rather than a village rushing under the mountain) is explicable from the vantage of distance, so too it is perfectly obvious that Madagascar has separated from Africa along the axis of the syncline in the southern position - palaeomagnetic 'evidence' or not.
Anyway, hidden in those measurements taken to "objectify the data" and purge it of all subjective influence is the randomising effects of surficial slumping and other crustal rotations that happened since the Curie point was frozen in the rocks, not the least of which are the trials and tribulations of trying to collect orientated samples in the first place (or worse, have others collect them for you). I reckon it's a wonder palaeomagnetic data even places Madagascar anywhere *near* Africa, .. which 'northerly position' makes me seriously suspect further finagling and cooking of the data. (... )
(Geology?) .. it's how it maps out that counts, .. how 'the data' is contextualised - scale and time and all that, .. not what you 'measure' (with all its inherent uncertainties) at a specific field location.
Fig.4 Near retrofit of Madagascar to Mozambique. Lighter colours (= Tertiary sediments) infill the 'scar' created as Madagascar recedes from Africa - or rather Africa recedes from Madagascar - is about 350-400km. Tertiary sediments filling the gap reflect falling sea-level /local isostatic correction as the Earth gets bigger. Note the ENE-WSW move is reflected in structure that spans from pre-Jurassic times (the intracratonic syncline of Jurassic volcanics preserved to the west) to post-Tertiary times (parallel coastlines) (Image base courtesy of Google Earth, geology courtesy of UNESCO.)
So there we have it, .. the simple commonsense, no-hypothesis needed, non-scientific ("Pssst"-in-your ear) picture : Madagascar as a crustal fragment detached from Africa as the Indian Ocean opened, and part of a much larger picture of crustal dilation. It fits, .. with the proviso that it overlaps some 400-450km of the Mozambique coast.
Which (overlap) is a nicety that would have scuppered Wegener totally at the time, because there is no coastline fit here whatsoever, .. but the geology , sequenced in time, fits very well. (Ask mother.)
[Added, 2012-09-15. (Loose talking here). I meant there is no fit of that syncline ('banana') with the coastline, so I guess I shouldn't say that, about "no coastline fit whatsoever", because the actual coastline of Neogene (yellow) and Quaternary (buff colour) sediments fits quite well with the banana, .. which shows the importance of flat detachments, basin subsidence and isostatic rebound of the pull-aparts.]
How many more suchlike overlaps (/duplications) (/isostatic adjustments) are hidden in the stratigraphic sequence, that support Earth expansion, and belie Plate Tectonics?
Lots. It's the whole story of geology that is yet to be properly contextualised, and has universally been overlooked; an Earth that is getting bigger.
Fig.5. Madagascar and Africa separation in relation to India is shown by the arrow, the trace of transforms in upper mantle between Madagascar and the Seychelles, those of the spreading ridge more generally, and the paired banks of the Seychelles and the Maldives representing an ancient position of Madagascar and India across the ridge. (Click for a bigger figure.)
In terms of global context, geology has hardly begun. And, .. since it's telling us the Earth is getting bigger, .. neither has physics. [link added 20170417; about 9:10 in, where she says, "It looks like we're going to have to start over", and he says, "Ya-ya."]
( Commonsense, .. see? )
[Added below, .. 2012-09-16 in answer to Anonymous, ..September 11, 2012 8:15 PM ]
(More on the Madagascar fit.)
Fig.6. More on the Madagascar fit. Bad and jangly on the left, smooth and good on the right. (Click image for a bigger one.)
Bad on the left. Is based on a common misunderstanding what transform faults are all about (Mental note to deal with later.) Transform faults are the trace of spreading *along* the ridges as much as they are *across* the ridge. The red interpretation denies the obvious structural connections in regard to the Great Rift Valley /African coast /Madagascar separation /Indian connection illustrated by Good on the Right. (And a whole lot more in the global context.) The Mozambique Basin (white) is the scar left on the mantle as Africa shimmied to the left on flat structures when it detached ("un-docked") from India, leaving the Moz. and Mad. Plateaus also as scars - which is why the left /south side of spreading on the Indian Ocean Ridge is more than on the north /right side. In other words, Africa probably separated from India, rather than the other way round, leaving the Seychelles and Madagascar in its wake. Similarly the Indian coast has shifted too from the Mascarene / Laccadives ridges.
Fig.7. Madagascar Separation according to the Davie Fracture Zone (a.k.a. "The Garden Path.") This is a classic example of thinking in a lobotomised way about detail ..that sees villages rushing under mountains, rather than looking with cognitive connection at the larger picture as in Fig.6 green above. (Reference : - Fig.1 :- http://www.sciencedirect.com/science/article/pii/S1464343X05002220
[Further update 2012-10-04 ]
Fig8. Gravity signature. The 'Davie Fracture Zone' (Fig.7) is paired with the Mozabique Escarpment to the west (yellow lines in (a) ). The rift separating Madagascar from Africa is a 'doppelganger' of the African Rift Valley to the west, and the Indian Ocean spreading Ridge to the east. (Click the image for a bigger figure.)
[ See also - Debunking Plate Tectonics - at :-