THE TOPOGEAPHY OF LAKE SHORES. 



47 



into deep water dnd thus lose their power to transport. Tlie variations 

 in the shapes of embankments have led to the recognition of various more 

 or less specific forms, such as spits, loops, bars, V-bars, etc., some of which 

 are described below. 



The building of eml)ankments can be best studied wheic there is an 

 abrupt change in the direction of the shore adjacent to a locality where 

 the formation of a sea cliff and its accomi)anying terrace is in progress. 

 Such au instance is illustrated in the following sketch-map : 



Fig. 4. — Skktch-map of ax Emba>'kment. 



The shore on the right of the cove is steej) and forms a sea cliff that rises 

 aljove a terrace along which the current travels in the direction indicated 

 l)y an arrow. Shore currents follow the broader outlines of the land, but 

 cut across bays and inlets. For this reason, in the case before us, the 

 sand and gravel swept along the surface of the terrace is carried into 

 deep waters and is deposited when the direction of the shore changes 

 abruptly, as the flow of the water is then checked. The terrace is pro- 

 longed as an embankment, having the same level, and is lengthened by 

 material carried along its surface and deposited at its distal extremity. 

 The construction of such an embankment is analogous to the manner 

 in which railroad embankments are made by carting dirt along them 

 fiom a cut and dum[)ing it at the end of the unfinished structure. In 

 cross sections an embankment shows a more or less perfect arching of the 

 material, and forming what may be termed an "anticlinal of deposition." 



In the ideal illustration here presented, it is evident that a continu- 

 ation of tlie process would result in the prolongation of the embankment 

 until it touched the shore at the left of the bay. The outline of the lake 

 would then Ijc simplified and a lagoon formed l)ehind the enil)aidcnient. 

 Should a stream enter such a lagoon, tlie water escaping from it might 

 ke(!i) a channel open to the lake, but a struggle would ensue between the 

 sliore currents tending to close the break and ihe outflowing water 

 striving to keep it ojieii. laddies in the coiillietlug eun'eiits would result 

 and lead to eliaiiLj-es in the outlines of the eiubankuieut. 



