38 Geology of Hudson County, Xew Jersey. 



side of the roud leading up to Union Hill, the stratified rooks 

 a,re once more exposed beneath the trap. At the " Hundred 

 Steps" abont forty feet of feldspatliic sandstone — arlcose — is ex- 

 posed beneath one hundred and ten or fifteen feet of trap ; tlie 

 junction between the two being so sharply defined that it may 

 be brought within the field of a mici'oscope, when a flake from 

 the surface of contact has been ground down so as to be trans- 

 lucent. 



About eighty yards northward of the high cliffs on which 

 the observing-tower stands, the face of the cliffs forms another 

 angle, where the trap once more breaks through and cuts off 

 the stratified rocks. 



Along the Union Hill road, opposite the porter's lodge of Mr. 

 King's estate, the stratified rocks when last seen are between 

 sixty and seventy feet above the river: crossing the little stream 

 known as the Awiehaken, and proceeding to the base of the 

 bold precipice forming King's Point, we find the trap breaking 

 through the sedimentary beds nearly on a level with the Hud- 

 son, showing that the main trap-sheet has shifted its position, 

 in reference to the stratified beds Avith which it is associated, 

 at least forty or fifty feet ; or, to speak more accurately, the main 

 trap-sheet has divided, sendijig out a branching layer of trtip 

 from the lower side. 



At the base of the cliff forming King's Point, the metamor- 

 phosed slates and shales below the trap are cut out, as 

 shown in the following section (Fig. 1), by the breaking through of 

 the trap ; the section exhibits, also, an intrusiA'e sheet of trap, an 

 offshoot from the large mass shown in the left of the section, 

 which is a little less than four feet thick ; the finely stratified 

 slates, both above and below this thin intruded sheet, are in- 

 tensely metamorphosed and have a jaspery structure. Tracing 

 this thin bed of trap towards the south, Avhere it approaches the 

 great dike, it cuts through the slates on which it rests, and 

 forces its Avay in betAveen the layer beloAV ; after this change, the 

 borders of the trap-sheet, as exposed in the face of the cliff, 

 are not well defined and are considerably contorted ; in places 

 masses of slate have been included in the trap. The Junction 

 of this small trap-sheet with the main dike is concealed by 

 debris. 



