Hmmm. The observed rate of ice buildup in that area is six to seven feet per year. Multiplied by 300 years and you get, what? 2000 feet! But it was less than 300 feet. Hmm. Must be about 50 years. But never mind the facts, just present your ignorant creationist web-site propaganda and hope nobody looks past it for the truth.
Try again. I went online and checked. The buildup in that area is 26cm or 10.4" water volume a year, and 5x that or roughly 52 inches of snow volume. You don't even get to 5 feet, much less the 6-7 feet you're claiming. You end up with 60 feet of snow volume unaccounted for in 48 years. You can't even get precision in the short term, in other words and want to sell it as accurate for millions of years. You have no basis for millions as it happens, so that isn't even worth addressing.