114 m:w vnijK sTATi-: Mrsi:r>[ 



liMUii as if siii-cadiii.u (uii <ni ilic low land ai ilic southern entrance 

 lo ilic Ili«»l»lan(l caiivon. li is reasonable lo snj>]K>se that at this 

 stMj^e tlic ice itrcssinii a^ainsi the northern sh)]K' of the Hi<;hhin(is 

 and liavin^i iliiniied loo ninch to th>\v over these rid<i;es forced a 

 h)nu ion.i:ne lliron^h the 1 1 i«»hlaii(ls conijiaraljh' to the ice streams 

 w liicli are jn-essed oul from I lie inland ice of (Ireenland to the west 

 roast. With this staj;e some of ihe higher terraces and morainal 

 dejjosils in Ihe II i;;li lands may he associated. Later the ice dwin- 

 dled away imdlinj* at snrface and also on its sides thus i)erniittin<»; 

 Ihe (h'position of <»ravels and sands about its margins and over 

 ihe rock terraces which at this stai>e bordered the dead ice in the 

 gorj^e. \\'ith the meltinj>' out of this ice, the glacial occupation of 

 the Lower Hudson was closed. 



An earlier chapter in the glacial occupation of the lower Hud- 

 son valley is recorded in the terminal moraine and possibly also 

 in the clays at Ilaverstraw which jire covered unconformahly by 

 later sands and gravels. If the view be correct that the terminal 

 moraine at the Narrows is the so called *' inner " or Cape Cod 

 moraine and that the "outer" or Nantucket moraine is to be 

 found overrun by ice and suffused in the region immediately north 

 of the Narrows it is probable that in the lower Hudson valley 

 as on the east in Massachusetts the ice advanced some distance 

 in taking up its position along both of these ice fronts. Con- 

 sidering these frontal moraines as respectively culminating the 

 earlier and (he later Wisconsin ejioch, in the intervjil between the 

 two episodes of southernmost j)rolongati()n of the ice front there 

 would be ()})portunily for the dejiosition of some of the older clays 

 which are found as far north as Haverstraw. On the other hand 

 it must be recognized that the advance of an ice sheet causes it 

 to overrun all dt^posits which have been laid down in front of it 

 in iis own time. It does not, therefore, from the evidence at hand, 

 appear iM>ssibie lo conclude definitely whether the Haverstraw 

 clays periain to the latest Wisconsin or to an earlier epoch. That 

 no clays are fonnd in the lower Hudson overlying the dei)0sits 

 coniein|toraii(Mnis with the ice fronts in the Hudson valley, makes 

 it e\i(leni at once that in this lield none of the geographic con- 

 ditions haxc pi-e\ailed which jtroduced the w idesjiread (days of 

 the nppei- llndson valley and (he Lake ('hami)lain district. 



