Abstracts
Abstract
Happing of quarternary deposits on the South Mountain Batholitb (SMB) has resulted in a four-fold subdivision of tills, divided prijuarily on the basis of clast lithology, texture, stratigraphic position and morphology.
Three tills have clast lithologles characterized by granites eroded from the South Mountain Bathollth. The oldest granite till is a compact till of restricted distribution, maiJily observed In druralin cores. Two younger granite tills dominate the surficlal deposits of portions of the SMB and have textural properties ascribed to melt-out tills. The fourth till represents a farther-travelled till with a variable clast provenance typified by pebbles derived from both the SMB and regions to the north. Clast dispersal evidence suggests that all tills were transported in a general southward direction.
Detailed clast examinations allow reliable conclusions concerning direction of Ice flow and llthologlc relationship between till and bedrock of the SMB. The SMB is an area of multiple glaciatlon where till prospecting cannot be successful unless the direction of till transport and source areas are established.
RESUME
Dn lev* cartographlque des depots quaternaires recouvrant le Batholite de South Mountain a permis de mettre en evidence quatre vsrletes de tills en fonctlon de la lithologie des clastes, la texture, la position stratlgraphlque et la morphologic
Dana trola tills, les clastes nontrent dea lithologles caracterlsees par des granites arraches au Batholite de South Mountain (BSM). Le plus vleux till de granite est un till tasse. de faible etendue, observe surtout dans les noyaux de drumlins. Dans certalnes portions du BSM, les depots de surface sont domlnes par deux tills de granite plus recents qui possedent des caracteristlques texturales rapportees aux tills d'ablation. Le quatrlerae till a pareouru une plus grande distance; la source de ses clastes est variable et comprend typiquement des galets provenant tant du BSM que des regions plus au nord. La dispersion des blocaux suggere un direction generale de transport des tills vers le sud.
Un exanen approfondi des clastes permet de tlxer de solldea conclusions a propos de la direction de 1'ecouleroent glaclalre et de la relation lithologique entre le till et le socle du BSM. Le BSM a subi de multiples glaclatlons et la prospection du till n'y est done guere profitable a molns de determiner la direction de transport et la source du till.
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