Fluvioglacial Floodplain, Kentville Bird Sanctuary EarthCache

Kentville Migratory Bird Sanctuary - Fluvioglacial Floodplain

The Kentville Migratory Bird Sanctuary (MBS) is located in Kentville, Nova Scotia. It offers a gathering site for many birds, such as waterfowl. This area is a 200-hectare floodplain with  grassy marsh containing many small, shallow ponds and backwaters of the Cornwallis river as it meanders along this area.

When the sandstones were first exposed as the basalt wore away, rivers flowed at right angles across the valley. These rivers rose on South Mountain and flowed north across the present valley and North Mountain before discharging into the centre of a river which flowed down the Bay of Fundy. The sandstone wore away more quickly than the basalt, and when the ends of the Valley became open to the sea, the drainage was diverted to the west and east. Sandstone is infrequently exposed within the Valley because it breaks down so readily to form a sandy soil.

The wetland area has been carved out by river action and deepened by glacial scouring. The Valley proper is defined as the area underlain by Triassic sedimentary rocks. It has created fertile wetland and is dominated by reed canary grass and a variety of other plants including blue-joint and spike rush as well as a wide variety of pondweeds and other aquatic plants that happily grow here.

Geology of the Floodplain area - Early Fluvioglacial Erosion

In geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluvioglacial is used.

Although some wetlands can form relatively quickly, many others took thousands of years to develop. River floodplains developed through erosion processes and through deposition of sediment on adjacent lands during floods. Wetlands form on floodplains where periodic flooding or high water tables provide sufficient moisture. These "riparian" wetlands may undergo constant change as rivers and streams form new channels and when floods scour the floodplain or deposit new material.

Glaciers helped to create wetlands in the north  9,000-12,000 years ago. Large wetlands formed when glaciers dammed rivers, scoured valleys, and reworked floodplains. Countless smaller wetlands formed when large blocks of ice left behind by receding glaciers formed pits and depressions in the land. Many of these depressions later filled with water if they had poor drainage or intersected the water table.

There are two major types of fluvial terraces: fill terraces and cut terraces. Fill terraces are formed as a valley or gorge is filled with alluvium. Alluvium can aggregate as a river meanders and overflows its banks, or it can be deposited by a glacier.  While fill terraces are associated with aggregation, cut terraces are associated with erosion. Cut terraces are often formed below fill terraces, as water erodes sediment. Older floodplains and river valleys can have many fluvial terraces.

To log this Earthcache visit the viewing location.  Please answer the following questions and send in a timely manner to my geocaching profile or email. Answers not received will result in deleted logs.

1 - On what side (N,S,E,W) of the river does the floodplain occur and Why?

2 - Was the floodplain formed from sandstone sediment or basalt?

3 - What is the elevation of the floodplain?

4 - Where does the water for the floodplain come from?

5 - Post a picture of the floodplain.

[REQUIRED] In accordance with the updated guidelines from Geocaching Headquarters published in June 2019, photos are now an acceptable logging requirement and WILL BE REQUIRED TO LOG THIS CACHE. Please provide a photo of yourself or a personal item in the picture to prove you visited the site.