Okay, first thing, it's promoting a book. This doesn't invalidate the ideas, but it's usually a warning. That said, I'll list the things I'm skeptical about. Doesn't mean they're wrong, simply means they send up red flags to be investigated more.
1) "The impact was supposed to be the site of Chicxulub, Yucatan, and now a multi-ringed crater is noted in the North Sea of approximately the same age. Yet, the Southern Hemisphere was just as devastated as the Northern Hemisphere."
The impact possibly could have set off the Deccan Traps in India, then I believe south of the equator and opposite the impact site. That, plus I don't believe the equator is as good a protector as once believed from global atmospheric disasters.
2) "The site of the proposed impact at Chicxulub, Yucatan, as part of the Caribbean Plate, was undergoing uplift, and plate rotation from the Pacific to the Atlantic during the Cretaceous, which is extremely difficult to reconcile with an impact."
Not sure why this would matter.
3) "Recent well coring at the Chicxulub (e.g., well log No.6) indicates that the structure may be volcanic or a cryptoexplosive geobleme (a structure caused by an explosion ejection from the Earth)."
Fair enough, but was that only one site? Hell of an ejection if that's true, but recent discoveries about places such as the Yosemite area would make me accept a buildup and eruption possible. However there's a lot of evidence to point to impact.
4)"Iridium is found almost globally and is found in strata that is not the same date everywhere, when it should be found mostly in the Yucatan region and bare the same date. The greatest abundance of iridium was found on the Hess Rise in the mid-Pacific, some 10,000 kilometers (6,200 miles) away from Chicxulub. In Raton Basin, New Mexico, the iridium was deposited during normal polarity of the geomagnetic field, not the reversed polarity of other sites. Many irregularities in iridium occur worldwide (by orders of magnitude)."
Last I read the iridium ages were very close in all areas found. It was the original smoking gun or extraterrestial origin of a global scale, and pointed to that single age. Maybe something new...?
5) "Some evidence indicates that the shocked quartz did not originate by impact, but may be volcanic or tectonic in origin."
Mentioned elsewhere about the Deccan
Traps, the site says that volcanic shocked quartz would be larger in size that impact, and be localized. However, the shocked quarz found accompanying the iridium layer globally is consistant with impact sizes.
6) "Some areas, such as at Gubbio, Italy, display a long interval of shocked minerals which is bisected by the boundary. Also at Gubbio, there are five iridium peaks, indicating the need for five impacts, and therefore, five craters with no other impact structure of the right age (with the possible exception of Manson Crater in Iowa). Similar extended zones can be found in the Pacific, Atlantic, Denmark, Spain, France, Germany and New Zealand."
Multiple impacts maybe. And craters are hard to find, look how long it took to find Yucatan's, as big as it is.
7)" In most situations the iridium and other noble metals are associated with organic compounds (kerogen and organic carbon or coal) from dead biomass, which is likely to be the source of the metals."
I thought iridium was rare on earth, period.
8) "The abundances of noble metals is more consistent with earthly compositions than extraterrestrial sources at many sites. Also other metals typical of meteoritic materials are missing in some sites with iridium or the ratios are not typical of impact debris. Moreover, the shocked quartz at some sites is more consistent with water transport (ocean erosion) rather than atmospheric (as would occur with impact)."
Not all meteors are the same. We're not experts on meteor consistance anyway, that's wht the NEAR mission was so important. And the impact was in water, with the resulting surge out and back into the crater. Could this account for what's found?
9) "Other times of impact did not cause such extensive mass extinctions."
Actually I think there's correlation in a few cases, the few big impacts we know of. The rest could be other factors, or lost evidence. 65 million years is relatively recent, and look how much debate it's causing.
10) "An impact is theoretically less likely to initiate widespread tectonic activity, and sea level rise, which occurred at the end of the Cretaceous."
Lot of energy, directed through the earth. Who's to say what will happen? How much experience do we have with impacts? Look at what happened on Jupiter, and that was a small comet, not solid. Actually, a solid might not have made as much of an explosion, but anyway...
11) "The climatic shift should have went from a drastic drop in temperature (with sunlight blocked) to progressively hot temperatures (the Greenhouse Effect). "
Not sure on this one myself.
12) "The mass extinctions of the time do not fit the impact theory: (a) The extinctions were not instantaneous and were selective. (b) Many species were in decline before the time of the proposed impact. (c) If the Yucatan region were the impact site then the greatest mass extinctions should be in southeastern North America, Central America, and northeastern South America, but were not (it seems that the greatest dinosaur fossil graveyard is in the Gobi Desert, on the other side of the Earth, and most extinctions were along mid-latitudes, not the tropics). (d) The huge dust and water vapor cloud should have caused plant extinctions the most, but it did not, and equatorial species should have been hit the worst, but it was mid-latitude species that were affected the most, and most mass extinctions were animals. (e) Photosynthetic nannoplankton survived into the Tertiary, and Cretaceous and Tertiary species even coexist in land-based marine sections of the Tertiary. (f) Tropical insects should have become extinct, but persist into the Tertiary. (g) The dinosaurs appear to have undergone gradual extinction in at least some locations."
Some good question here, I'd have to research more to argue them. One thing, "The extinctions were not instantaneous and were selective", one of the arguments for the theory this site pushs is why some fossils have been found in the opposite, suddenly killed, in mid battle for one. It's arguing both sides it seems. Wouldn't a shockwave moving at the speed of sound, plus the sudden heat blast, instantly kill those exposed?
13) "High-energy terrestrial explosions, called geoblemes or cryptoexplosions, have not been studied, nor have laboratory simulations been tested. Therefore, much of the evidence for impact is somewhat biased by not considering the evidence in light of all the possibilities. For example, a number of journal articles have shown that the craters on Mars and other planets are dynamically related to the core, and therefore, are internal in origin. Also, the structural similarities of multi-ringed craters with a central peak are too uniform, regardless of size and proposed angle of impact, for them to be impact craters; laboratory experiments show different structures for different angles and impactor size. This suggests that multi-ringed craters with a central peak, like that of the Chicxulub, are internally produced."
There are craters such as this on the Moon, which is dead. I thought the argument of craters being volcanic had been done away with years ago.
That's enough (probably too much) for now. What evidence of radiation deaths is there among dinosaurs anyway? That seems to be the biggest argument going for this theory, but how do you preserve evidence of this?