Saturday, March 9, 2013

Iowa Impact Crater

Had Russia’s 55 foot wide meteor not smacked into Chelyabinsk recently, it is doubtful you would hear about the Iowa event on this blog. After all, an asteroid strike in the United States as wide as a city block puts the Russian event to shame. Before becoming too alarmed, we must announce the object we reference struck land in what is now the United States up to 450 million years ago. We must also announce that the crater was filled with sediment many years ago. Its circular image is apparent to instruments sensing variations in gravity and electrical conductivity.

The children of Decorah, Iowa may be excited to discover they live in a 3½  mile wide asteroid crater more than 700 feet deep, underlain by a type of rock containing tiny “shocked” quartz crystals. Such crystals are only typical of powerfully impacted rocks. During the Ordovician geologic period lasting from 488 to 443 million years ago, there were no land animals to observe this grand event. All life was confined to the oceans. There may be several other craters in the US to provide evidence for celestial impactors during that time frame. The meteor impacts may or may not have contributed to the second largest extinction event on planet Earth. Nevertheless, extinction events on this planet have been an important contributor to the rapid appearance of new life forms to replace species going extinct.

I visited Meteor Crater in Arizona during the 1960s. This privately owned site is touted as the best preserved meteor crater on earth. My personal observations of the crater affirm this claim. The impactor struck several tens of thousands of years ago. The crater is almost one mile wide, 550 feet deep, and 2.4 miles in circumference. For thousands of years it has not been obliterated by the effects of earth’s erosion and weathering. Therefore, it remains a gigantic testament to the wondrous events still prevalent in our cosmos.  

A very well publicized extinction event occurred about 66 million years ago. The impact event is theorized to have caused the extinction of dinosaurs and other genera on earth in a brief moment of geologic time. Nobel prize-winning physicist Luis Alvarez and his team hypothesized a devastating asteroid strike in Central America. The debris of iridium, a cosmic element, was found in rock layers spread around the earth. It is theorized to be debris from the impact. Evidence of the giant asteroid strike is centered in the Yucatan Peninsula town of Chicxulub, Mexico. While this event is not the most severe extinction event to engulf our earth, the changed global conditions were suddenly fatal for the bizarre dinosaurs countless numbers of our children have learned to love.

Geological periods are usually demarcated by great extinctions. Such events are most often triggered by environmental transformations. Astronomical or geological events trigger sudden, worldwide climate changes. A large asteroid impact or widespread volcanism could cause a few degrees of cooling resulting in an ice age. Worldwide extinctions could result. As we study these events, what facts impact us most? The answer lies in the events following the extinctions. Multiple examples of rapid radiations exist following earth’s extinction events. In radiations new species quickly repopulate the earth to replace the extinct species. Evolutionists credit a naturalistic process for the species changes. Creationists incorporate divine creation events in their explanatory model of new species appearances on the earth.

The Central America impact event of 66 million years ago ended the Mesozoic era, the age of dinosaurs. But the Cenozoic era, immediately following, saw a rapid radiation of mammals and birds. The first chapter of Genesis verses 20-31, chronicles the creation of living creatures, including humans. Genesis 1 is the story of creation of life. Scripture tells us that life on earth originated in supernatural events of creation during days five and six. The Bible uses the Hebrew term yom to designate creation time periods. Many geological and astronomical events have punctuated earth history both before and after life was created on earth. Natural events in God’s extraordinary providence have worked ultimately for the benefit of man and the good of all living creatures in his created world.