Probably cause of niagra falls has something to do with it. not sure though
The oceanic lithosphere consists of the upper part of the Earth's crust that is submerged beneath the oceans. It is primarily made up of basalt, but can consist of other forms of sediment deposited by rivers or currents; the basalt feature exists due to the oceanic lithosphere's creation via divergent tectonic activity. The continental shelf is a portion of the crust that is of higher elevation than the rest of the ocean due to its connection to the less dense continental lithosphere. The continental slope, therefore, is the portion of the crust where the continental shelf decreases in elevation as it meets the denser oceanic lithosphere. Abyssal plains are portions of the lithosphere far from spreading centers - they consist of rocks older than those near rifting centers. Due to the coolness of the plate and their distance from rifting centers, abyssal plains are some of the lowest continuous portions of the lithosphere (cool rock is denser and thus sinks to a lower elevation). Since they are very much inactive, abyssal plains are coated with sediment and are very, very flat.
The correct answer is - A) Permafrost used to be permanent.
The permafrost used to be permanent until recently, so using certain techniques of building on it functioned properly. But with the climate changes that are becoming more and more evident, the permafrost is no longer permanent, but instead, it is either defrosting in some part of year and then forming again, or has been totally absent from some regions in the present.
That has caused changes in the rules governing building on permafrost. The reason for the changes is that the old techniques do not work properly anymore, and the permafrost changes are making change in the landscape, making big damages on the infrastructure in meantime.
Alfred Wegener found this out through the Continental Drift Theory.
