42 RO>TF. MODERN nOCK-BriLDING. 



least ri -e of wiiieh occurs at the moon's (luartcrs, known a^ neap 

 tides, the water lie-ins its retreat while still several feet l)elow 

 the marsh level. 



As a result of the great rise of tide the currents in the rivers 

 and half-emptied Ijay are of great swiftness. Here, too, is a large 

 quantity of quicksand, — sands which the waters have gained 

 possession of as a result of the pulverizing power of the waves 

 and other agenci*^s on the rocks of the bay shore. These sands 

 are continuallv being carried to and fro by the flowing and ebb- 

 ing tide. By the resulting attrition the sands are still further 

 pulverized into an almost impalpable detritus. With this detri- 

 tus the water becomes charged and gains its chocolate colour, 

 and the further we ascend the tidal streams the more heavily is 

 the water charged. 



At high water during the period of spring tides large areas, 

 are overflowed by the muddy waters, and during the short inter- 

 val, while the water is at rest, a large part of the detritus settles 

 and is deposited, forming one layer of alluvium , It is in this 

 way that the whole of these alluvial marshes have been made. 

 One layer of alluvium is in thickness from an inch dow'n. The 

 total depth of alluvium varies from the thinnest layer at the head 

 of the tide to 40 feet at the mouths of some of the rivers. 



There are reasons to believe that the lower layers of the deep- 

 er alluvium were deposited on subsiding upland soil. In one 

 locality near a channel were found stumps of beech, pine and 

 other upland trees many feet below^ the marsh and tidal levels. 

 In many places are found roots of trees W'hich could not live sub- 

 ject to overflow by salt water. 



The marsh deposits began then as soon as ihe areas now 

 covered w'ith alluvium were low enough to be overflowed. As 

 the subsidence continued the depth of deposit increased. These 

 deposits in some cases have been sufficient to check the upward 

 flow of tidal waters in river valleys and allow the subsiding areas 

 above to receive a fresh water or lake deposit. An interesting 

 Instance of this is the area in the basin of the River Missiquash, 

 now under the control of the Missicpuish Marsh Improvement 

 Company. Most of this area until very lately has been, as far 

 back as popular records go, covered with fresh water, forming a 

 series of lakes joined into one large one in times of freshet. When 



