1898] MARYLAND ACADEMY OF SCIENCES. 399 



and that it has not taken millions of years to complete the 

 structures now in view. Still further, if we accept the 

 time it has taken to fill the basin of the West Branch of 

 the Patapsco River ten feet, as well as the estuaries of 

 the broad creeks which formerl}^ poured large volumes 

 of water into the Patuxent and Potomac rivers, we shall 

 find that the past fifty years have sufficed to fill up these 

 water courses. Vast changes in the surfaces of our land 

 and water have taken place within that time. The drying 

 up of springs along the courses of our creeks and rivers, 

 taken alone, shows a loss of fiix.y per cent, in the volume 

 of water within the last forty years. The filling up along 

 the shores of our Spring Gardens, and at the mouth of 

 Gwynn's Falls, and on the Patapsco river during the last 

 thirty-five years has added hundreds of acres to the lands 

 of property owners there. Were the bed of the West 

 Branch of the Patapsco river, above the Light street 

 bridge, raised twelve feet above its present level, a section 

 of mud, clay and sand would be exposed, very similar to 

 that which we see in the formation at the foot of South 

 Eutaw street. Strong floods in the streams backed against 

 high tides have, in recent times, cut away and trimmed off 

 the projecting ends and sides of many banks of clay 

 which stood in their way along our rivers, near Baltimore, 

 and have thus eroded wide areas for the entrance of the 

 tides. Later, however, these spots have generally been 

 covered with sediment washed down from the higher 

 lands, aided by gentle overflows of the tides, until now 

 these tracts lie above the reach of the highest overflows. 

 Examples of this kind may be seen at the mouth of 

 Gwynn's Falls, Herring Run, Gorsuch's Creek, head of 

 Back river, and Patapsco river, near the crossing of the 

 Annapolis railroad, besides many other places on the 

 tributaries of the Chesapeake, north of that river. 



Three strata of this group of deposits have thus fai 



