My son asked me about why we have saltwater oceans and freshwater lakes in relation to the flood and creation. When the flood waters receded, where did freshwater come from? Why would God create the earth with such an abundance of saltwater as compared to freshwater? How were the land locked saltwater lakes/seas formed? I am not overly knowledgeable on the theological and scientific answers to these questions. Thanks
I assume that the original oceans were not salty. Water washing from land masses into the ocean carries sodium, chloride, potassium and other ions which make it salty. I assume you are aware that there is a water cycle which takes the water which enters the oceans, and returns it to the land through evaporation and precipitation. In the process of evaporation the salt is left behind. It has been estimated that the total amount of salt now in the oceans would require somewhere around three hundred million years to accumulate at the current rate of transfer into the ocean from the earth’s rivers. Geologists agree that in the deep past there was less total land area which means that less salt entered the oceans during earlier times. Besides, occasionally, parts of the ocean become separated and salt is deposited which explains some of the huge salt domes which are found under the ground.
Landlocked salty water bodies were created the same way the salty ocean was created, except much faster. The Dead Sea and the Great Salt Lake both exist in very arid basins into which water flows and from which evaporation is very rapid, making these salty lakes accumulate their saltiness much faster than the oceans. I am not an expert, so I cannot tell you how fast the Dead Sea or the Great Salt Lake could accumulate their salt, but I assume it is tens or hundreds of thousands of years, not many millions of years. Fresh water bodies are ones with water flowing out of them, which, of course, is most lakes.
As for the flood, the Bible does not give us sufficient details to know for sure where the water came from and where it went to. I assume that the entire event was a miracle. I believe that there is no natural explanation of the flood. I believe in the flood principally because it is recorded in the Bible. The exact nature of the flood, how deep the water actually was, and how much of the earth was actually inundated is an open question in my opinion, but that God judged the earth and the people on the earth in the flood is something I believe because it is recorded in the scripture.