How To Identify a Hindostan Whetstone Marker Erik Kvale Richard L. Powell Indiana Geological Survey Whetstone headstones are characterized by three distinct physical qualities. All three of these physical features must be present before one can be certain the marker in questions is actually a Hindostan Whetstone marker. First, they are generally more weather resistant than contemporary local sandstone markers and far more weather resistant than limestone and marble markers that supplanted them in the early 1850's. Most of the pre-Civil War marble headstones are no longer legible and vintage limestone markers are little better. Most of the whetstone markers appear as if they were engraved a few years ago rather than 150 to 170 years past because their fine-grained nature and resistance to weathering allowed for the carving and preservation of some exquisite motifs and lettering. "Hindostan" whetstones owe their resistance to weathering from its composition of predominantly quartz grains. Quartz is a mineral that is very resistant to weathering. These grains are cemented together by a "glue" also composed of quartz. The whetstone monuments contrast markedly from the marble and limestone material used later in the 19th century by monument dealers. The marble and limestone materials are composed primarily of calcium carbonate or lime that is very reactive to acid rain. As a result these younger monuments are very weathered and, in most cases, difficult to read. Second, the color of a whetstone monument, usually tan, but including off-white, buff, light brown and some partly rust streaked, is n contrast to the darker brown and red sandstones or white to gray marble or grey limestone. Whetstone headstones can typically be distinguished from other types of markers from a few hundred feet away. Third, but most important, when viewed on-edge, each marker exhibits a sequence of relatively thick and thin layers that are characteristic of Hindostan Whetstone. The alternate thick-thin siltstone layers resemble stacked interleaved thick and thin cardboard sheets. A thick-thin pair is often referred to as a "couplet." Besides forming couplets, the layers show a progressive overall pattern of thickening and thinning. The Hindostan Whetstone siltstones formed on an ancient tidal flat when Indiana had beach-front property approximately 300 million years ago during a period of time referred to as the Pennsylvanian Period. The formation of the couplets and the progressive thickening and thinning was a direct result of twice-a-day fluctuations in flood-ebb tidal currents as the sediments were deposited on a silty tidal flat. Although it is not necessary to understand how the whetstone thick-thin layers formed, it is very important to be able to recognize them for no other material used for grave markers in southern Indiana is known to have this characteristic. The number of couplets (one thick and one thin layer) seen on whetstone headstones has been as few as nine and as many as 32 within the space of about two and a half inches.