346 HATCHER — MARINE AND NON-MARINE FORMATIONS. [April 7, 



2, would, of course, be limited if, as we assumed above, perfectly 

 stable conditions of the earth's surface were maintained in this 

 region during the entire period required for the eastward extension 

 of the coast line from its present position to that of the eastern bor- 

 der of the submerged continental plateau. Above No. 3 would 

 come No. 4, the uppermost of the series, a fresh water and to 

 some extent aeolian deposit, with its beds of peat transformed per- 

 haps into lignite and remains of a terrestrial and fresh water verte- 

 brate and invertebrate fauna. The thickness of these fresh water 

 deposits would not be limited as would that of Nos. 2 and 3 of the 

 series, since as the coast line advanced eastward it would leave 

 behind a low and flat region growing continually wider from east to 

 west and increasing very slowly in elevation by the accumulation 

 over its surface of fluvial, lacustrine and aeolian deposits. As the 

 width of the coastal plain increased the inclination of its surface 

 toward the sea would become less and less and the drainage or run- 

 off would be reduced to a minimum, transforming the region into 

 one of 'lakes and marshes connected by sluggish streams and 

 increasing its capacity for the accumulation of fresh water and 

 aeolian deposits. By the uninterrupted continuance of such condi- 

 tions these deposits would go on accumulating over this entire 

 region long after the shore line had advanced far to the eastward of 

 its present limits, resulting in a greater thickness of fresh water and 

 aeolian deposits along the western than along the eastern border. 

 These deposits would therefore form an overlying wedge with the 

 blade directed eastward, or in a direction opposite to that of the 

 wedge of marine deposits constituting No. i at the base of the 

 series, and tending to produce a somewhat uniform thickness of the 

 combined series of beds, with the fresh water deposits predominating 

 in the western region and the true marine deposits in the eastern, 

 while the interstratified brackish water and littoral deposits would 

 continue practically of the same uniform thickness from the eastern 

 to the western border of the region. 



Thus far we have only considered what would take place here 

 under perfectly stable conditions in the earth's crust. Let us next 

 consider what would result from certain oscillations in the earth's 

 surface along this coast. 



If a period of elevation should set in affecting the coastal plain 

 and submerged continental plateau the effect would be to hasten 

 the recovery of the continental plateau from the sea and to decrease 



