The rocks which underlie Button Bay State Park can be seen along the small creek which is located just south of the Park. It is suggested that the visitor walk southward (to the right if approaching the road from the lake front) along the main park road until the first culvert beneath the road is reached. Looking down the creekbed toward the lake, one can readily see the older rocks (see A, Figure 11). _Fossils_[18] are found in these tilted rocks which tilt or dip toward the northeast and “strike” northwestward. Fossils date the rocks underlying Button Bay State Park as Middle _Ordovician_.[19] The most abundant fossil is a trilobite, _Triarthrus_, but, even this ancient _arthropod_[20] is not easily found in these limestones and limy shales. A sketch of _Triarthrus_ (that portion found fossilized) appears in Plate 1. These rocks containing _Triarthrus beckii_ belong to the Stony Point formation and are of late Sherman Fall or Denmarkian age. One of the jobs of the geologist is to reconstruct the paleogeography (ancient geography) of a region. The different kinds of rocks present and their distribution patterns, together with the types of fossil plants and animals found, tell the geologist of past lands and seas, warm and cold climates. The rocks of the Stony Point formation (the rocks which underlie most of the Park) tell of warm marine waters, a past sea, bordered by relatively low land areas. The fossils contained in the Stony Point formation attest to the presence of relatively shallow marine waters. The fact that these Ordovician rocks are tilted and broken by faults proves that _major earth movements_[21] took place sometime after their lithification. [Illustration: _PLATE 1_] 1A, B, C; _Maclurites magnus_ Lesueur (X 0.5). Lower, upper and side views. Crown Point limestone. GASTROPOD (snail). 2; _Triarthrus beckii_ Green (X 3). Top view of central part of head region. Stony Point shale. TRILOBITE. 3; _Saxicava_ (X 3). Pleistocene marine clays. PELECYPOD. 4; _Macoma_ (X 3). Pleistocene marine clays. PELECYPOD. 5A, B; _Rhinidictya_ (X 9 and X 1). Orwell limestone. BRYOZOAN. 6A, B, C: _Cryptolithus tesselatus_ Green (X 2). Top, side and front views. Glens Falls limestone. TRILOBITE. 7; _Rafinesquina._ Internal view. Orwell and Glens Falls limestones. BRACHIOPOD. [Illustration: _FIGURE 11_ GEOLOGIC MAP OLDER ROCKS] (fault) CROWN POINT LIMESTONE CHAZY (VALCOUR?) (Clay covered in most areas) ORWELL LIMESTONE (clay covered) GLENS FALLS LIMESTONE (clay covered in most areas) (fault) STONY POINT FORMATION (clay covered in most areas) GEOLOGY NORTH OF PARK BOUNDARY ADAPTED FROM CHARLES W. WELBY—1961