the grand canyon couldn't be carved by a very small river of water. and, you can trace the path of least resistance - when there was a huge amount of water. what does this tell you? that no water was involved? the river suddenly became huge (by a combination of the ocean floors letting up 'fountains' from the deep and massive downpours of rain) with pressure and a massive amount of dirt and rock being carried with it. usually the way rocks are degraded is either by massive earthquake, volcano, or flood (which the canyon floor could have cracked from earthquake- and pieces of it separated - so i believe all three happened) - but what caused the tiering? the erosion wasn't simply wind - to have it end up looking the way it does today. the most amount of water pressure would be highest up. that is where there is the most amount of rock that was carried away. otherwise - the canyon would be steep gorges that are straight down and fairly close together (according to the cracks you see - type california - earthquake faults).
secondly, God was very patient and it was not his first intention to flood the earth. this man starts off with a wrong premise. God wanted to flood the earth. NO. he didn't want to. it grieved his heart. in fact, He waited for 100 years! genesis 5:32 says noah was 500 - when he had his sons and began work on the ark. genesis 6:10 was the same time that noah was 'commissioned' and God wanted him to be an example or witness to the people around him. but, they laughed. they didn't believe.
so, noah had basically 100 years to deal with all these so called 'problems.' but, think of it - building the ark was not a smple job. as mentioned, it had to not only be watertight - but able to handle bumps and scratches of a very high probability during the first very violent part of the flood. in fact, that it was able to come through the flood was a miracle in itself - no matter how well it was built.
now, another matter which makes me think this man didn't even bother to read the biblical account - is that only the unclean animals went in 'two by two.' the clean (edible animals) went in by sevens. seven pairs - if you read hebrew. why? because they needed to sustain their population at the same time as being used for food after the flood by noah and his family and the human population to come. as well, as natural predators.
one matter, that seems obvious, too - is that this man is criticizing what didn't even happen. 'if people went and gathered the animals...' the fact of the story is - they didn't. so why blab about that for awhile? God had 100 years to bring animals from every part - although sloths didn't have to live in brazil at that time. if the earth was still one continent (as one continent people like to believe - and perhaps has something to do with the idea of peleg and the'earth dividing' - at the time of the tower of babel - after human migration to different areas) - then the animals would not have had to travel over water. they merely walked or flew from A to B as God directed them to migrate. how far a sloth can migrate in a period of time before dying - is certainly a good question. but, not impossible for God. why? because God could simply make a sloth appear out of nowhere and stick it on the ark. but, He did it the long way. the sloth made a slothful move every day towards the ark. laugh if you must.
but, in gen 7:6 - it says 'now noah was six hundred years old when the flood of water came upon the earth. if the sloth wasn't terribly far - noah could have carried him the last two feet. (or 300 miles). perhaps he did a 'last roundup?' anyways - enoch was carried away in a whirlwind - what would stop God from doing the last roundup himself? i don't know any more details than what is in the bible. as i see it - there are no facts with evolution. the bible is fact. the more you read it - the more you see that God can do pretty much whatever He wants. there is an element of 'freedom' in His ability to create and design and do. He is God.
evolution would say - flood. meh. but, it doesn't account for recent findings with human migration according to mtDNA. we've traced back to eve of noah's flood (noah's wife) and the age of the earth is still young.
also, what accounts for strange artifacts from one area - being plopped down in a very strange other area of the world. animals, artifacts, etc. - some extremely heavy. like obelisks from alexandria ending up in waters near greece. recently some were transported back to alexandria (that were TONS).
there is a layer of sediment - completely around the world - that proves the flood happened. as the water settled into various places - it formed seas. the black sea is obviously a result of a flood. and, what would account for salt mines being found in the midst of dry areas such as africa and other places? where did these massive amounts of salt come from?
lastly, but rather only because i am tired - there are various settlements that archeologists uncover from periods before the flood (neolithic) - but, that do not appear elsewhere on earth dated this far back in the same manner of building? why? maybe because God created mankind at eden which is most likely the mouth of the rivers of iraq - where they converged. this piece of archeological research was uncovered in turkey:
https://www.turkishdailynews.com.tr/article.php?enewsid=54909