If a true valley is a lowland between ranges of hills or mountains that protrude above the surrounding elevation, then the Qu'Appelle is less a valley than a great groove set into the level plain.
- Trevor Herriot - River in a Dry Land
The area that is now the Qu'Appelle Valley was created during the last ice age, 14,000 years ago. This time period is called the Quaternary Period, and represents only a very minute amount of the earth's history. While it is such a small time frame, the Quaternary Period was the time period in which most of the present land features in Canada were formed.
The present landscape was built entirely of material that was deposited by glaciers during the last ice age. In places these deposits are 273 meters thick. During the Quaternary Period, the province of Saskatchewan was covered on four occasions by glaciers. As each glacier advanced, it eroded the surface, picking up rocks and materials deposited by previous glaciers. It transported these materials over long distances; for example, some of the erratic boulders were originally from Manitoba. When the glaciers melted, they produced so much meltwater they eroded the channel of water that eventually became the Qu'Appelle Valley. Each time the glaciers melted, some of the material trapped within the ice was deposited along the earth's surface, forming layers of soil. After the last glacier melted, the Qu'Appelle Valley was entirely filled with water.
Valleys
A valley is an extended depression in the Earth's surface that is usually bounded by hills or mountains and is normally occupied by a river or stream. Because valleys are usually occupied by a river, they can also slope down to an outlet which can be another river, a lake or the ocean.
Valleys are one of the most common landforms on the Earth and they are formed through erosion or the gradual wearing down of the land by wind and water. In river valleys for example, the river acts as an erosional agent by grinding down the rock or soil and creating a valley. The shape of valleys varies but they are typically steep-sided canyons or broad plains, however, their form depends on what is eroding it, the slope of the land, the type of rock or soil and the amount of time the land has been eroded.
There are three common types of valleys which include V-shaped valleys, U-shaped valleys, and flat-floored valleys.
V-Shaped Valleys
A V-shaped valley, sometimes called a river valley, is a narrow valley with steeply sloped sides that appear similar to the letter "V" from a cross-section.
They are formed by strong streams, which over time have cut down into the rock through a process called downcutting. These valleys form in mountainous and/or highland areas with streams in their "youthful" stage. At this stage, streams flow rapidly down steep slopes.
An example of a V-shaped valley is the Grand Canyon in the Southwestern United States. After millions of years of erosion, the Colorado River cut through the rock of the Colorado Plateau and formed a steep-sided canyon V-shaped canyon known today as the Grand Canyon.
U-Shaped Valley
A U-shaped valley is a valley with a profile similar to the letter "U." They are characterized by steep sides that curve in at the base of the valley wall. They also have broad, flat valley floors. U-shaped valleys are formed by glacial erosion as massive mountain glaciers moved slowly down mountain slopes during the last glaciation. U-shaped valleys are found in areas with high elevation and in high latitudes, where the most glaciation has occurred. Large glaciers that have formed in high latitudes are called continental glaciers or ice sheets, while those forming in mountain ranges are called alpine or mountain glaciers.
Due to their large size and weight, glaciers are able to completely alter topography, but it is the alpine glaciers that formed most of the world's U-shaped valleys. This is because they flowed down the pre-existing river or V-shaped valleys during the last glaciation and caused the bottom of the "V" to level out into a "U" shape as the ice eroded the valley walls, resulting in a wider, deeper valley. For this reason, U-shaped valleys are sometimes referred to as glacial troughs. One of the world's most famous U-shaped valleys is Yosemite Valley in California. It has a broad plain that now consists of the Merced River along with granite walls that were eroded by glaciers during the last glaciation.
Flat-Floored Valley
The third type of valley is called a flat-floored valley and is the most common type in the world. These valleys, like V-shaped valleys, are formed by streams, but they are no longer in their youthful stage and are instead considered mature. With these streams, as the slope of a stream's channel becomes smooth, and begins to exit the steep V or U-shaped valley, the valley floor gets wider. Because the stream gradient is moderate or low, the river begins to erode the bank of its channel instead of valley walls. This eventually leads to a meandering stream across a valley floor.
Over time, the stream continues to meander and erode the valley's soil, widening it further. With flood events, the material that is eroded and carried in the stream is deposited which builds up the floodplain and the valley. During this process, the shape of the valley changes from a V or U shaped valley into one with a broad flat valley floor. An example of a flat-floored valley is the Nile River Valley.
Rivers
Rivers provide us with food, energy, recreation, transportation routes, and of course water for irrigation and for drinking. But where do they start and where do they end?
Rivers begin in mountains or hills, where rain water or snowmelt collects and forms tiny streams called gullies. Gullies either grow larger when they collect more water and become streams themselves or meet streams and add to the water already in the stream. When one stream meets another and they merge together, the smaller stream is known as a tributary. The two streams meet at a confluence. It takes many tributary streams to form a river. A river grows larger as it collects water from more tributaries. Streams usually form rivers in the higher elevations of mountains and hills.
The areas of depression between hills or mountains are known as valleys. A river in the mountains or hills will usually have a deep and steep V-shaped valley. The fast moving river picks up pieces of rock and carries them downstream, breaking them into smaller and smaller pieces of sediment. By carving and moving rocks, running water changes the earth's surface even more than catastrophic events such as earthquakes or volcanoes.
Leaving the high elevations of the mountains and hills and entering the flat plains, the river slows down. Once the river slows down, the pieces of sediment have a chance to fall to the river bottom and be "deposited". These rocks and pebbles are worn smooth and get smaller as the water continues flowing.
Most of the sediment deposition occurs in the plains. The wide and flat valley of the plains takes thousands of years to create. Here, the river flows slowly, making S-shaped curves which are known as meanders. When the river floods, the river will spread out over many miles on either side of its banks. During floods, the valley is smoothed and tiny pieces of sediment are deposited, sculpting the valley and making it even smoother and more flat. An example of a very flat and smooth river valley is the Mississippi River valley in the United States.
Eventually, a river flows into another large body of water, such as an ocean, bay, or lake. The transition between river and ocean, bay or lake is known as a delta. Most rivers have a delta, an area where the river divides into many channels and river water mixes with sea or lake water as the river water reaches the end of its journey. A famous example of a delta is where the Nile River meets the Mediterranean Sea in Egypt, called the Nile Delta.
From the mountains to the delta, a river does not just flow - it changes the surface of the earth. It cuts rocks, moves boulders, and deposits sediments, constantly attempting to carve away all of the mountains in its path. The goal of the river is to create a wide, flat valley where it can flow smoothly towards the ocean
Most rivers have an upper (youthful) course, a middle (mature) course and a lower (old age) course. These stages are marked by variations in the characteristics of the river.
The first stage of stream development is youthful. This usually takes place in a V-shaped valley and is characterized by steep channels and a straight gradient. There are no floodplains or meanders at this stage, and the stream is still developing its channels. It is rare to see floodplains at this point, and if there are any they are very small. One example is rapids.
At the mature stage, streams begin to show signs of bends and curves, which are known as meanders, and floodplains start to develop. The gradient, velocity and discharge become moderate, and they are present in valleys and hills that are rounded.
By the old stage, streams have clearly defined floodplains and the meanders are very pronounced. Old streams feature slower velocities, reduced gradients and greater discharge. This discharge begins to deposit on the side of the streams in the form of sand and other types of sediment. When the local area experiences heavy rainfall, old streams burst their banks. In some cases, streams deviate from some of their meanders to follow a new stream channel. These meanders are usually visible in the landscape and will eventually become the new channel, cutting off the old channed and forming an oxbow.
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