170 NEW YORK STATE MUSEUM 



selected the former and entered the swamp region of Wood creek, 

 following this creek with its immature swampy drainage up toward 

 the Hudson. Here it was extremely easy to impede his progress 

 by cutting trees and throwing them across the road, an opportunity 

 of which the Americans made the fullest use. Burgoyne wasted 

 months of valuable time and his best energy and provisions in 

 these swamps of glacial origin. When he finally reached the 

 Hudson he followed it on the east side until he found the place 

 where at Thomson the river falls over a ridge of harder Normans- 

 kill shale below which a bridge could be easily built. After cross- 

 ing he was again forced to the river bank by the only road avail- 

 able, while deep ravines cut into the thick clays of Lake Albany 

 made excellent opportunity for a defensive position for the Ameri- 

 can army. Such a position was selected at Bemis Heights. 



On the other side of the river towers Wlllard mountain, an 

 erosion remnant due to the hardness of the grits and cherts of 

 Normanskill age that compose the syncline. From this bold 

 mountain every movement of the British army could be easily seen 

 by the patriot Willard and signalled to General Gates. 



After his defeat, Burgoyne retreated leisurely and sullenly up 

 the river. Hessian officers advised him to leave his cannon and 

 baggage behind and save the army by a forced retreat by way of 

 Lake George, but the obstinate though brave general decided to 

 return by the crossing at Thomson, allowing by his slow and unde- 

 cided action the Americans to overtake him and, in using the 

 peculiarly favorable topography of the locality, which is due to its 

 remarkable geology, to prepare a trap for him. The most important 

 feature of this topography is that just above the Thomson crossing 

 a volcanic rock, known as the Northumberland volcanic plug, juts 

 out prominently toward the river, so that it has complete com- 

 mand of the crossing and at the same time prevents an army from 

 passing under it at the west bank of the river. This important 

 strategic point was occupied by Colonel Stark. It, and Fellows's 

 batteries which could be advantageously placed on the bluffs of 

 Albany clay on the opposite bank of the river, were, with Morgan's 

 sharpshooters in the woods to the west of the army, the principal 

 means of forcing Burgoyne to surrender. Thus we see that the 

 peculiar combination of a ford over a shale ridge, a volcanic rock 

 close by and bluffs of clay aided greatly in bringing about the 

 decisive victory of Saratoga. 



