Kā Roimata o Hine Hukatere or Franz Josef Glacier, located in New Zealand's stunning Westland Tai Poutini National Park offers an ever-changing landscape of glacial features that captivate thousands of manuhiri (visitors) each year. From the mesmerising blue ice caves to the treacherous crevasses and towering seracs, these formations are not only breathtakingly beautiful but also critical for orientation and exploration on the glacier. In this blog post, we'll look at what these glacial features are and how they are formed.
What Is a Glacial Feature?
A glacial feature, also known as an ice formation, refers to the various structures and shapes formed within a glacier. These features are created by the dynamic processes of the glacier's movement and the interaction of ice with environmental factors. Some of the most notable glacial features include:
- Crevasses: Deep, vertical cracks in the glacier
- Seracs: Towering pillars of ice
- Ice Falls: Cascades of ice resembling frozen waterfalls
- Ice Caves: Tunnels and caverns within the ice
These features serve as landmarks for navigation and are spectacular to witness first-hand on the glacier.
How are glacial features formed?
Glacial features are primarily shaped by two forces: pressure and water. Each of these forces plays a crucial role in sculpting the glacier’s landscape, leading to the formation of various ice structures.
The role of pressure
Pressure is a dominant force in the creation of glacial features. Glacial ice, despite appearing solid and stable, is actually quite brittle. As the glacier moves downhill, it encounters numerous obstacles such as cliff faces, and large rocks hidden beneath the ice. These obstacles create stress and tension within the ice, causing it to crack and break. This process results in the formation of several key features:
- Crevasses: As the glacier flows, differential movement rates within the ice cause it to stretch and compress. The edges of the glacier, which move slower due to friction with the valley walls, create tension with the faster-moving centre. This tension leads to the formation of crevasses, which can be narrow and shallow or wide and deep, depending on the underlying obstacles and the stress applied.
- Seracs: When multiple crevasses intersect, the ice between them can remain standing as isolated blocks or towers, known as seracs. These formations can be incredibly tall, sometimes reaching the height of multi-story buildings. However, seracs are inherently unstable, particularly when exposed to the warmth of the sun, which can cause them to collapse without warning. But don’t worry your guide will keep you safe from these.
- Ice Falls: These dramatic features occur where the glacier flows over steep cliff faces, creating a cascade of ice that resembles a frozen waterfall. The constant movement of ice over these cliffs results in a chaotic jumble of crevasses and seracs, forming a rugged and continually shifting landscape.
The influence of water
Water also plays a critical role in shaping glacial features, especially at lower altitudes where the glacier is more exposed to warmer temperatures. The Franz Josef Glacier, ending at less than 1,000 meters (3,280 feet) above sea level, experiences significant daily temperature fluctuations. During the day, the surface ice melts, creating pools of water that refreeze at night. This cycle of melting and freezing leads to the formation of distinctive features:
- Moulins: These are vertical shafts within the glacier, formed by water that melts its way down through the ice. They act as conduits for surface water to travel to the base of the glacier.
- Ice Caves: Also known as blue ice caves, these are formed by water flowing through the glacier and melting tunnels and chambers within the ice. The blue hue of these caves comes from the dense ice absorbing all colors of the spectrum except blue.
The Ever-Changing Landscape
The Franz Josef Glacier is a dynamic and living landscape, continuously reshaped by the forces of pressure and water. This constant change means that no two days on the glacier are ever the same, providing endless opportunities for discovery and adventure. Our guides are experts in understanding the formation and behaviour of these glacial features ensuring our manuhiri have a safe and exciting experience.
Visiting the Franz Josef Glacier offers a unique glimpse into the powerful natural forces that shape our planet. Whether you're navigating around a crevasse, marvelling at the height of a serac, or exploring an ice cave, each feature tells a story of the glacier's ongoing journey. This remarkable landscape, with its stunning and sometimes perilous features, promises an unforgettable adventure for all who brave its icy expanse.