After serving in the U.S. Army for three years in World War II, Dan In 1960, Dan graduated from Wheaton College, followed by a M. Div and Th. M. from Central Baptist Seminary, followed some years later by a research-master's degree in biology from Ohio University. He then taught for  five years at Wingate College in North Carolina, followed by seven years at Grace College in Indiana, where he helped to establish a standard biology department.

In 1973 he left full-time teaching to devote the remainder of his life to the study of sedimentary geology and the teaching of how it helps us to understand and appreciate the Biblical account of creation.

Betweem 1974 and 1977 he wrote the book God's Time-Records in Ancient Sediments to explain to Christians what the sedimentary rock layers of the earth are like, and why most of them required long periods of time to be deposited and converted into types of rock. In his own words,  "Helping Christians to learn this kind of information has been my primary work since 1973, and this work is needed more now than ever. Christians need to reject evolutionism, but when they reject true scientific discoveries they bring disgrace upon the Bible and Christianity."

Dan opposed the "misunderstanding which was being promoted by extreme creationist leaders in many of the Christian schools and colleges of the U.S. and Canada." His conclusions are found in his second book, Neglect of Geologic Data: Sedimentary Strata Compared with Young-Earth Creationist Writings, which he first published in 1987.

In both of these books, Dan was obsessed with ensuring the complete accuracy his assertions from geology, and he submitted his writings to the review of experts in the geologic field.

In addition to these two books, Dan also wrote a number of reviews and short papers, some of which are listed below.