Text & Photos by Gavin John
Earth resides in what scientists commonly refer to as the goldilocks zone, being neither too hot nor too cold to sustain organic life. It also is universally rare in that it contains water in all three states, namely ice, liquid and gas due to the proximity of its orbit around the Sun. And it is water in its ice form that helped shape the outer surface of the Earth via a process known as Glaciation.
Glaciers form when the rate of accumulated snow fall exceeds the ablation rate (the loss of ice from melting, runoff and evaporation.) The snow forms layers of ice which once sufficiently massive form long frozen rivers of ice that are dragged down to sea level by gravity.
Glaciers prevail during Ice Ages with the last major ice age, the Pleistocene period commencing two million years ago. During this period glaciers formed within five degrees of the equator, but now cover a mere ten percent of the Earth’s surface. Their size can vary from small masses of ice inhabiting a single valley to super massive continental glaciers ranging up to five million square kilometres.
Glaciers comes in many shapes and forms and have occurred in all regions of the Earth but are now mostly found nearer the poles and in high areas. Most of Earth’s glaciers are currently in retreat but many, including Argentina’s Perito Moreno glacier feature here, still have stable ablation rates, and some are even advancing in regions such as Alaska. The speed at which glaciers move is determined by various factors including the gradient on the valley floor, the temperature and depth of ice and the friction on the valley walls. Their speed is typically around a meter per day but some have been measured travelling thirty meters a day.
Glaciers are categorised into many types such as hanging glaciers which reside high up in the valleys they have carved out of a mountain, Piedmont glaciers which forms when one or more valley glaciers flow from a confined valley onto a plain where they expand, and the majestic tidewater glaciers which terminate in a body of water such as a glacial lake where they carve off magnificent icebergs which float away into rock floured lakes.
This author considers glaciers to be nature’s most beautiful constructs. In fact glaciers are beautiful even when they are no longer still present leaving behind breathtaking valleys and spectacular fjords. While living glaciers are by no means uninteresting rivers of ice. The pure white ice is highlighted with striking blues tones created by the dense ice absorbing and striping out every other colour in the visible spectrum.
Glaciers also are host to impressive features which are depicted in these photographs. Structures such as the towering seracs; crevasses; ice caves; moulins; snow bridges; ice falls; and swathes of lateral, medial and terminal moraine defining their boundaries. All conclude with a stunning Terminal Face, delineating the extent of the glacier.
Not just visually satisfying. Glaciers additionally create incredible sounds, especially near the terminal face when cracking can be heard hidden within, and thunderous roars erupt as massive chunks collapse from the terminus.