The geomorphic evolution of limestone pavements and alvar grasslands in Northwestern New York State, United States of America

In the mid 1980s seven natural grasslands were discovered in the forest biome of northwestern New York State. The grasslands are part of an alvar landscape, an ecological community of open grassland and savanna on thin soils over carbonate bedrock that are limited to the Great Lakes and Baltic regions. This dissertation research of The Nature Conservancy's Chaumont Barrens Preserve concentrated on the geographic distribution, geomorphic evolution, hydrology, and water chemistry of the pavement karst landscape.; The Chaumont Barrens is on a low upland interfluve of gently folded Middle Ordovician limestone. Solutionally enlarged joints (grikes) that survived complete Wisconsinan glacial planation were covered with diamicton and lacustrine sediments when Lake Iroquois flooded the site beneath ca. 100 m of water. Lacustrine sediments deposited throughout the region were subsequently eroded from the Barrens (and similar uplands) by wave action associated with lower lake levels. A thin, winnowed diamicton remains on the Barrens on much of the bedrock, and organic-rich soils have developed on mechanically weathered bedrock.; Relict grikes beneath the originally calcareous diamict facilitated the leaching of carbonates in the diamict, which inhibited significant dissolution of the underlying bedrock surface. As a result, pedestals are not present on the Chaumont Barrens, despite an estimated 21.5 cm (19.5 mm ka{dollar}sp{lcub}-1{rcub}){dollar} of denudation in the past 11,000 years. Dissolution was expended on detrital carbonates in the drift. Grikes also allowed for sapping of clastic cover and exposure of the glacially planed bedrock surface as pavements. Bedrock pools have CO{dollar}sb2{dollar} concentrations below atmospheric because of algal photosynthesis; CO{dollar}sb2{dollar} recharges at night. Evaporation and subsequent deflation of precipitated CaCO{dollar}sb3{dollar} can lead to kamenitza formation.; Holocene erosion of drift exposed the pavements and led to clastic filling of grikes. The exposed pavement surface mechanically decayed at a rate greater than chemical dissolution of the bedrock surface creating a limestone rubble and a root zone suitable for grasses. Disintegration of the bedrock surface aided in grike filling, reducing infiltration rates, creating a diffuse recharge system, and causing surface water to pond in grasslands during spring and fall wet seasons. The extreme swing in hydrologic conditions in the thin soils maintains the grassland environment.