The incoming tide rushes up the Minas Basin near Wolfville, Nova Scotia, Canada. The Bay of Fundy and its tributaries have the world's greatest tidal variation, rising and falling twice a day at a normal walking pace. Acadians of the 18th century built dikes to keep the tide waters out, creating farmland and preventing land-use conflicts with the nearby Mi'kmaq population.

Photograph by Ben Farmer

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  • The Minas Basin, part of the Bay of Fundy in Nova Scotia, Canada, is home to the most dramatic tidal range in the world. Tides, moving as fast as a person can walk, rise and fall as much as 14-16 meters (46-52 feet) every day.

    This photograph was taken at low tide, exposing the wide, extensive mudflats of the Minas tidal basin.

    The Minas Basin is an estuary. It forms at the mouth of the Cornwallis River, where it empties into the Bay of Fundy and the Atlantic Ocean. Like many estuaries around the world, the mudflats of the Minas Basin are blanketed by thick layers of bay mud.

    Bay mud has many unique characteristics. It is often saturated with moving water, creating extremely fine-grained sand particles. It has a high concentration of clay, mostly from silty river deposits. Bay mud also contains sediments carried by glaciers during the last ice age. This all combines to create very soft, flexible mud.

    Layers of bay mud are classified according to their age. Quaternary older bay mud—layers from the Ice Age and earlier is abbreviated QoBM. Quaternary younger bay mud is abbreviated QyBM. Layers of QyBM can be as thick as 8 meters (25 feet), while layers of QoBM can be more than 55 meters (180 feet).

    1. Do you think these mudflats are good places to farm?

      Answers will vary.

      No: The extreme tides and lack of dry soil make it impossible to farm on the Minas Basin mudflats.

      Yes: Dikes have been used throughout the coastline of the Bay of Fundy. These levees block the tides and "reclaim" low-lying mudflats for agriculture and development. Similar land reclamation is common in places such as the Netherlands (where levees block the North Sea) and along the Mississippi River basin in the United States.

    2. Do you think mudflats are good places for industry?

      Answers will vary.

      No: Bay mud is far too soft and flexible to provide a stable foundation for most large, heavy buildings. Structures built on bay mud in seismically active areas, such as the San Francisco Bay Area, are especially vulnerable.

      Yes: Engineers can secure a building's foundation to harder, more stable rock beneath the layers of bay mud. Sometimes, these features, called pilings, can reach more than 30 meters (100 feet) below ground.

    3. Bay mud is divided into Quaternary old bay mud (QoBM) and Quaternary younger bay mud (QyBM). Which layer do you think lies deeper underground?

      QoBM was deposited hundreds and even thousands of years before QyBM. It is a much deeper layer of sediment, found underneath QyBM.

  • Term Part of Speech Definition Encyclopedic Entry
    bay mud Noun

    thick deposits of soft rocks (mostly clay, silt, and sand) that form around some bays and estuaries.

    characteristic Noun

    physical, cultural, or psychological feature of an organism, place, or object.

    clay Noun

    type of sedimentary rock that is able to be shaped when wet.

    estuary Noun

    mouth of a river where the river's current meets the sea's tide.

    Encyclopedic Entry: estuary
    glacier Noun

    mass of ice that moves slowly over land.

    Encyclopedic Entry: glacier
    ice age Noun

    long period of cold climate where glaciers cover large parts of the Earth. The last ice age peaked about 20,000 years ago. Also called glacial age.

    low tide Noun

    water level that has dropped as a result of the moon's gravitational pull on the Earth.

    mouth Noun

    place where a river empties its water. Usually rivers enter another body of water at their mouths.

    Encyclopedic Entry: mouth
    mudflat Noun

    coastal wetland formed as rivers or tides deposit sediment.

    sand Noun

    small, loose grains of disintegrated rocks.

    saturate Verb

    to fill one substance with as much of another substance as it can take.

    sediment Noun

    solid material transported and deposited by water, ice, and wind.

    Encyclopedic Entry: sediment
    silt Noun

    small sediment particles.

    Encyclopedic Entry: silt
    tidal basin Noun

    depression in the earth that fills with water at high tide.

    tidal plain Noun

    large, flat area where mud and sediment are deposited by ocean tides. Also called tidal flat or mudflat.

    tidal range Noun

    the difference in height between an area's high tide and low tide.

    tide Noun

    rise and fall of the ocean's waters, caused by the gravitational pull of the moon and sun.

    Encyclopedic Entry: tide