In my new book, Improbable Planet, I list and describe eleven different reasons why a human civilization sustaining billions of humans would be impossible if it were not for our living at the end of a highly fine-tuned ice age cycle. Now, a scientific research team has discovered a twelfth reason.1 An especially strong ice age cycle, like the one we are in now, generates many large gravel-bed river floodplains, which prove to be ecological bonanzas.

An ice age cycle is an ice age where the amount of ice coverage on Earth’s surface cycles between about 10 percent and 15–25 percent. Such a cycle has been in effect for only the last 0.00057 part of Earth’s history. It came about as a result of the Sun reaching the midpoint of its burning history and five simultaneous very rare and very dramatic tectonic events. I describe these extraordinary circumstances in my book, Improbable Planet.2 However, until just 800,000 years ago, the ice age cycle’s period was too brief to produce the benefits required for a global human civilization. Furthermore, only the last deep ice age in the cycle yielded all the benefits necessary for global human civilization to be possible. We are living in the only interglacial period in the ice age cycle—and for that matter, in the entire history of the earth—during which billions of humans could receive God’s gift of redemption!

We should thank God for the ice age cycle because such a cycle produces many long-lasting gravel-bed river floodplains. Such floodplains only occur in glaciated mountain landscapes. Melting glaciers, especially valley glaciers, in mountain ravines and canyons result in water, rocks, gravel, and silt to spread out in valleys below the mountains. Such landscapes are characterized by four highly differentiated seasons. These seasonal differences produce “dynamic fluvial processes that constantly change and renew the surface and subsurface of the river’s valley floor.”3

The featured image for this blog shows a photo I took of a gravel-bed river floodplain in southern British Columbia. This floodplain was generated by the melting of North America’s southernmost ice field, the Conrad Icefield in Bugaboo Provincial Park. The waters of this floodplain constitute one of the sources of the Columbia River.

For the first time, an interdisciplinary research team—that involved hydrologists, avian ecologists, fresh water biologists, and large mammal ecologists—worked together both to study the geological and ecological dynamics of gravel-bed river floodplains and to take an inventory of all the benefits such floodplains bring. They found that these floodplains support an unexpectedly high number of species. Specifically, they determined these floodplains are “focal points for biodiversity in maintaining viable aquatic, avian, and terrestrial populations.”4

The following is a list of the unique benefits accruing from gravel-bed river floodplains that the research team has discovered to date:

  1. The floodplains provide a unique habitat that sustains a much larger number of aquatic, avian, and terrestrial species than the surrounding regions.
  2. They serve as a connectivity zone linking the surrounding habitats and the species they contain.
  3. They efficiently recycle life-critical nutrients.
  4. The nutrient-rich waters below and lateral to the main water channels support a complex web of abundant microbes, insects, and crustaceans which in turn sustain large populations of fish, amphibians, birds, and mammals.
  5. The downwelling water from the surface channels into the gravel beds below carry large amounts of dissolved and particulate organic material which sustains microbial decomposers that release biologically available nitrogen and phosphorus.
  6. The floodplains yield nutrient-rich resources that sustain aquatic insects and other invertebrates that inhabit the gravel beds from valley wall to valley wall of the floodplain, which provide a food chain base for fishes, amphibians, bats, birds, and both small and large mammals.
  7. The periodic flooding and groundwater-to-surface-water exchanges generate optimal spawning habitats for a wide variety of fish species.
  8. The trees that fall into the river and stream channels as a result of cut-and-fill alleviation events create shaded water pools which protect fish and other species from harmful summer heat.
  9. The combination of large-scale floods, cut-and-fill alleviation events, and wild fires create a highly productive, highly diverse vegetation community which sustains large-bodied mammal herbivores and large-bodied mammal carnivores.
  10. The compression of elevation differences within small areas establishes large moisture gradients that further enhance the diversity of plant species.

The team further noted that without floodplain habitats many large-bodied mammal species, for example, moose, beaver, and river otters, would not survive. They also observed that top predators, such as wolves, critically depend upon gravel-bed river floodplains for their food. They estimated that 40 percent of all kills by wolves occur on gravel-bed river floodplains.


Image 1: Town of Field and the Trans-Canada Highway Disturb the Ecosystem of the Kicking Horse River Gravel-Bed Floodplain Ecosystem
Image Credit: Hugh Ross

The team closed their research paper with an appeal. They pointed out that modern humans have undervalued the importance of gravel-bed river floodplains. The erecting of dams, towns, highways, and other structures in gravel-bed river floodplains (see image 1) greatly diminishes the ten benefits listed above. However, there would hardly be any gravel-bed river floodplains at all if it were not for our living in an ice age cycle with a periodicity of about 100,000 years (and where the last ice age in the cycle manifested the greatest extent of ice). As I explain in my book, Improbable Planet, there would be no ice age cycle, let alone one that generates all the gravel-bed river floodplains that currently exist on Earth, if it were not for the simultaneous occurrence of five miraculous and unprecedented tectonic events that are timed at the just-right point in the Sun’s nuclear burning history.5

Thank God for the ice age cycle! Thank God for our living at the just-right time in the ice age cycle that we are blessed with so many large, nutrient and ecologically rich gravel-bed river floodplains.


  1. F. Richard Hauer et al., “Gravel-Bed River Floodplains Are the Ecological Nexus of Glaciated Mountain Landscapes,” Science Advances 2 (June 2016): e1600026, doi:10.1126/sciadv.1600026.
  2. Hugh Ross, “Ready for Occupancy,” chap. 15 in Improbable Planet (Grand Rapids: Baker, 2016).
  3. Hauer et al., “Gravel-Bed,” 1.
  4. Ibid.
  5. Ross, “Ready for Occupancy,” chap. 15 in Improbable Planet.

Subjects: Design, Earth, Ecosystems, Fine-Tuning, Geology

Check out more from Reasons to Believe @

About The Author

Dr. Hugh Ross

Reasons to Believe emerged from my passion to research, develop, and proclaim the most powerful new reasons to believe in Christ as Creator, Lord, and Savior and to use those new reasons to reach people for Christ. I also am eager to equip Christians to engage, rather than withdraw from or attack, educated non-Christians. One of the approaches I’ve developed, with the help of my RTB colleagues, is a biblical creation model that is testable, falsifiable, and predictive. I enjoy constructively integrating all 66 books of the Bible with all the science disciplines as a way to discover and apply deeper truths. 1 Peter 3:15–16 sets my ministry goal, "Always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have. But do this with gentleness and respect, keeping a clear conscience." Hugh Ross launched his career at age seven when he went to the library to find out why stars are hot. Physics and astronomy captured his curiosity and never let go. At age seventeen he became the youngest person ever to serve as director of observations for Vancouver's Royal Astronomical Society. With the help of a provincial scholarship and a National Research Council (NRC) of Canada fellowship, he completed his undergraduate degree in physics (University of British Columbia) and graduate degrees in astronomy (University of Toronto). The NRC also sent him to the United States for postdoctoral studies. At Caltech he researched quasi-stellar objects, or "quasars," some of the most distant and ancient objects in the universe. Not all of Hugh's discoveries involved astrophysics. Prompted by curiosity, he studied the world’s religions and "holy books" and found only one book that proved scientifically and historically accurate: the Bible. Hugh started at religious "ground zero" and through scientific and historical reality-testing became convinced that the Bible is truly the Word of God! When he went on to describe for others his journey to faith in Jesus Christ, he was surprised to discover how many people believed or disbelieved without checking the evidence. Hugh's unshakable confidence that God's revelations in Scripture and nature do not, will not, and cannot contradict became his unique message. Wholeheartedly encouraged by family and friends, communicating that message as broadly and clearly as possible became his mission. Thus, in 1986, he founded science-faith think tank Reasons to Believe (RTB). He and his colleagues at RTB keep tabs on the frontiers of research to share with scientists and nonscientists alike the thrilling news of what's being discovered and how it connects with biblical theology. In this realm, he has written many books, including: The Fingerprint of God, The Creator and the Cosmos, Beyond the Cosmos, A Matter of Days, Creation as Science, Why the Universe Is the Way It Is, and More Than a Theory. Between writing books and articles, recording podcasts, and taking interviews, Hugh travels the world challenging students and faculty, churches and professional groups, to consider what they believe and why. He presents a persuasive case for Christianity without applying pressure. Because he treats people's questions and comments with respect, he is in great demand as a speaker and as a talk-radio and television guest. Having grown up amid the splendor of Canada's mountains, wildlife, and waterways, Hugh loves the outdoors. Hiking, trail running, and photography are among his favorite recreational pursuits - in addition to stargazing. Hugh lives in Southern California with his wife, Kathy, and two sons.

Email Sign-up

Sign up for the TWR360 Newsletter

Access updates, news, Biblical teaching and inspirational messages from powerful Christian voices.

Thank you for signing up to receive updates from TWR360.

Required information missing