Lidar provides detailed insight into sedimentary rock successions in mountainous regions with extensive cover. Lidar penetrates thin soils and forest cover, “exposing” bedrock for the first time. Texture shading of lidar enhances changes in slope and is not limited to a single direction of artificial illumination like hillshade images. Variations in resistance to erosion are clearly visible and highlight subtle features.

An estimated 2.4 km thickness of rocks occur in the Catskill Mountains, eastern New York. They record the history of Devonian terrestrial settings from ca. 388 to 374 Ma, including Earth’s oldest known fossil forest. The stratigraphic/sedimentologic record of these strata can be observed by viewing lidar data from a horizontal perspective using Natural Scene Designer, a commercially available program. This makes it possible to correlate individual layers across mountains.

Prominent horizontal ledges of various thicknesses and lateral continuity in lidar images are fluvial channel sandstones, with the percent conglomerate increasing upward through the succession. Intervening horizontal intervals with relatively few features correspond to floodplain mudrock-dominated facies.

Vertical trends include repeating packages of multiple layers. Some are dominated by channel sandstone ledges; some represent multiple-stacked sandstone bodies. Other intervals are dominated by thick successions of floodplain mudrocks, with few thin channel sandstones that laterally pinch out and disappear.

Terrestrial sequence stratigraphy models state sea level changes on the lower slopes of an alluvial plain-slope system are the dominant influence on sedimentation trends. This is the setting of lower strata of the Catskills. Deposition of sandstone-rich intervals are interpreted to have been deposited during times of  lower sea level. More mudrock-dominated intervals were deposited during times of higher sea level.

Locally, billowy masses of rock are visible, which extend only short distances laterally. Erosionally down-cut, unconformable surfaces are also visible locally. Both features demarcate incised valleys, formed during sea level low stands.

Other features visible on slopes include thicker Pleistocene to recent sediments, too thick to be penetrated by lidar. Human infrastructure is also visible in lidar images and can easily be distinguished from natural features.

High-resolution texture shade images viewed from a horizontal perspective make it possible to analyze sedimentary packages in areas of thick cover in unprecedented detail, and to understand sea level changes in the Catskill delta in a new way.