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CROSS REFERENCE TO PRIOR APPLICATION 
   This application is a continuation-in-part of prior application Ser. No. 09/798,210, filed Mar. 2, 2001, now U.S. Pat. No. 6,651,401 entitled RETAINING WALL AND METHOD OF WALL CONSTRUCTION. 

   FIELD OF THE INVENTION 
   This invention relates generally to the construction of retaining walls used in landscaping applications where such walls are used to provide lateral support between differing ground levels. More particularly, the present invention relates to a retaining wall that uses a series of differently sized, pre-formed horizontal and vertical blocks that operatively connect with each other along adjacent courses to resist pressure exerted against the wall by retained back-fill material and ground water. 
   BACKGROUND OF THE INVENTION 
   Retaining walls are widely used in a variety of landscaping applications. Typically, they are used to maximize or create level areas and also to reduce erosion and slumping. They may also be used in a purely decorative manner. In the past, retaining wall construction was labor intensive and often required the skills of trained tradespeople such as masons and carpenters. More recently, retaining wall construction has become significantly simplified with the introduction of self-aligning, modular, molded blocks of concrete that may be stacked in courses without the use of mortar or extensive training. With these types of blocks, it is possible to erect a retaining wall quickly and economically, and the finished product creates the impression and appearance of a conventional block and mortar retaining wall. The feature that allows such blocks to be so easily and precisely assembled is the interconnection between adjacent courses of blocks. Typically, each block will include a projection and a recess located at oppositely facing surfaces, such as a top surface and a bottom surface, for example. The projection and recess are complimentarily shaped, with the projection protruding beyond the bottom surface of the block and with the recess extending inwardly from the top surface of the block. In use, a projection of a first block is received within the recess of a second block to interconnect and position the blocks adjacent each other in a predetermined relation. With a plurality of blocks, such interconnections make it possible to lay courses of blocks in an accurate and expedient manner. Moreover, such an assembled retaining wall is able to resist lateral forces exerted by the material being retained and reduce bowing. Blocks having these interconnections are usually the same size and may be assembled in a coplanar arrangement in only a simple, running bond pattern. In a variation of the aforementioned blocks, the projection and recess may be arranged so that adjacent courses are offset a predetermined amount. With this type of block, each successive course may be offset from the preceding course by the same amount so that the assembled wall is skewed at a predetermined angle from the vertical. These blocks also have the same dimensions to enable them to set in only a simple, running bond pattern. 
   A recent development in mortarless retaining walls has been the advent of blended pattern retaining walls. These walls differ from the aforementioned walls in that the preformed blocks used to construct a retaining wall are differently sized. This feature allows retaining walls to be assembled in a variety of patterns and bonds. Usually, these types of preformed blocks are horizontally and vertically oriented and have dimensions that are based upon an incremental unit such as the thickness of a horizontal, preformed block. For example, the thickness of a horizontal block is one increment and the height of a vertical block is two increments. With these types of preformed blocks, it is possible to construct a retaining wall with no discernable courses. A drawback with such a retaining wall is that setbacks are not possible and the assembled retaining wall must be substantially vertical. Alternatively, a retaining wall may be arranged in thick courses, and the blocks within these thick courses may be randomly arranged. For example, a course may be two incremental units high within which the differently dimensioned preformed blocks are arranged. Or, the course may be three incremental units high within which the differently dimensioned preformed blocks are arranged. There are several drawbacks with this type of wall. One drawback is that the vertical blocks dictate the height of the course. Thus, if vertical blocks are used, each entire course must be coplanar and all of the blocks must lie in the same plane. Otherwise, the projections of blocks in one course would not be able to be received within the recesses in blocks of another course, and the interconnection would be defeated. Another drawback with such this type of wall is that the number of arrangements available within each course is limited, and a truly random arrangement is not possible. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention comprises a plurality of horizontally elongated and vertically elongated, preformed blocks that may be assembled to form a retaining wall. Each horizontal preformed block includes a front member and a rear member connected to each other by a web, opposing sides, a top portion and a bottom portion. The horizontal blocks may be formed in a series of predetermined incremental thicknesses whose additive thickness is equal to the height of the vertical block. For example, the horizontal blocks may have incremental thicknesses of one, two and three units, while the vertical preformed block is three units tall. Thus, the horizontal blocks may be stacked in whatever units which, when added together, would be three units tall. 
   The front member of each horizontal block includes a rearwardly facing portion having stop surfaces that are aligned with each other and are used to operatively connect adjacent courses of blocks. Each horizontal block also includes a recess and a projection located at oppositely facing support surfaces, respectively. Preferably, the recess is located at the top of each block and extends downwardly with respect to the top support surface of each block forming a through slot with open ends in spaced relation to the front member of each block. An important feature of the recess in these blocks is that the recess includes a stop surface that is in alignment with stop surfaces of the rearwardly facing portion of the front member of each block. Together, these stop surfaces form a single stop surface that extends substantially along the length of each horizontal block. This greatly increases the utility of each block because it allows the blocks of an adjacent upper course of blocks to be slidingly positioned with respect to a lower course of blocks as the retaining wall is being constructed. This adds to the number of possible arrangements of blocks and helps one construct a stronger retaining wall because aligned vertical joints between adjacent courses may be easily avoided. 
   The projection on the horizontal block extends downwardly with respect to the bottom surface of each block. Preferably, the width of the projection is substantially equal to the width of web that connects the front and rear members together. Each projection includes an indexing surface that is configured to operatively contact a stop surface of an adjacent course of blocks. 
   Each vertical preformed block includes a front member and a rear member connected to each other by upper and lower webs, opposing sides, a top portion and a bottom portion. The front member of each vertical block includes a rearwardly facing portion having a stop surface. Each vertical block also includes a recess and a projection located at oppositely facing support surfaces, respectively. Preferably, the recess is located at the top of each block and extends downwardly with respect to the top support surface of each vertical block forming a through slot with open ends in spaced relation to the front member of each block. The recess in these blocks includes a stop surface that is coincident with the stop surface of the front member, and, as with the horizontal blocks, the stop surface extends substantially along the width of each vertical block. 
   As with the horizontal block, the projection on the vertical block extends downwardly with respect to the bottom surface of each block, and preferably its width is coincident with the width of the vertical block. Each projection of the vertical block also includes an indexing surface that is configured to operatively contact the stop surface of an adjacent course of blocks. 
   Another important feature of the aforementioned blocks relates to the operative connections that occur between the projections and recesses of adjacent courses of blocks. This is achieved by using blocks that have a stop surface which is fixed relative to a common feature of the blocks, such as the viewable surface, and blocks which have indexing surfaces located at a series of predetermined distances from a common feature of the blocks, also such as the viewable surface. For example, to construct a coplanar wall, one would select those blocks where the indexing surfaces are at a first predetermined position. Alternatively, to construct a wall that tilts at a slight angle with respect to the vertical, a different set of blocks with indexing surfaces located at a second predetermined position would be used. And, to construct a wall which tilts at a greater angle with respect to the vertical, yet another set of blocks with indexing surfaces located at a third predetermined position would be used, and-so-on. This feature may be combined with the other features discussed above to produce a myriad of retaining wall configurations that may include combinations with different setbacks and/or no setbacks. 
   An object of the present invention is to provide a retaining wall that may be assembled without the use of mortar. 
   Another object of the present invention is to increase the number of arrangements possible between adjacent blocks in a retaining wall. 
   Yet another object of the present invention is to reduce undesired lateral movement between adjacent courses in a retaining wall. 
   A feature of the present invention is that vertical, preformed blocks have a height that is equivalent to two or more stacked horizontal preformed blocks. 
   Another feature of the present invention is that the horizontal, preformed blocks may have the same thickness or may have complimentary thickness whose additive thickness is equal to the height of vertical, preformed blocks. 
   Another feature of the present invention is that the courses of blocks may be assembled in a coplanar or one of several predetermined offset relations. 
   An advantage of the present invention is that the use of differently sized and oriented preformed blocks permits a retaining wall to be configured into a myriad of configurations. 
   Another advantage of the present invention is that each course presents a substantially contiguous, aligned stop surface against which indexing surfaces of projections of an adjacent course of blocks are positioned. 
   Additional objects, advantages and features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combination particularly pointed out in the appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a front, perspective, partial view of one embodiment of a completed, coplanar retaining wall of the present invention; 
       FIG. 2  is a perspective view of an embodiment of the preformed blocks of the present invention taken from a position in front of and above the block; 
       FIG. 3  is another perspective view of the block of  FIG. 2  taken from the same position, with the block in an inverted and outwardly facing orientation; 
       FIG. 3  is another perspective view of the block of  FIG. 2  taken from the same position, with the block in an inverted and outwardly facing orientation; 
       FIG. 4  is a perspective view of another embodiment of the preformed blocks of the present invention taken from a position in front of and above the block; 
       FIG. 5  is an inverted perspective view of the block of  FIG. 4  taken from a position in front of and above the block; 
       FIG. 6  a partial side view illustrating a first setback and the interface between adjacent courses of blocks; 
       FIG. 7  is a partial side view illustrating a second setback and the interface between adjacent courses of blocks; 
       FIG. 8  is a partial side view illustrating coplanar alignment and the interface between adjacent courses of blocks; 
       FIG. 9  is a side elevational view of an embodiment illustrating various setbacks which are possible with the blocks of the present invention; 
       FIG. 10  is a front, perspective, partial view of an embodiment of a completed, variable setback retaining wall of the present invention; 
       FIG. 11  is a front perspective view of an embodiment of a retaining wall with horizontal blocks stacked one above the other in a columnar fashion in accordance with the present invention; and 
       FIG. 12  is a front perspective view of an embodiment of a retaining wall with horizontal blocks stacked one above the other in a running bond fashion in accordance with the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   With reference to the drawings,  FIG. 1  shows one embodiment of a retaining wall  10  comprising a plurality of horizontally and vertically oriented preformed blocks  30 A,  30 B,  30 C, and  90  of the present invention. As will be discussed later in greater detail, the horizontal, preformed blocks  30 A,  30 B, and  30 C may be formed in different incremental thickness, and are combinable so that their total thickness is equal to the height of the vertical, preformed blocks  90 . As shown in  FIG. 1 , the horizontal, preformed blocks  30 A,  30 B,  30 C may be selected and stacked in combinations of twos and threes. That is, block  30 A and block  30 C, two blocks of  30 B, and three blocks of  30 C. It will be understood, that each course of blocks may be defined by the height of the vertical blocks  90 . Thus, beginning with the lower left segment of the wall  10 , the first course  12  comprises two stacked  30 A blocks, a vertical block  90 , two stacked  30 A and  30 C blocks, two stacked  30 C and  30 A blocks, a vertical block  90  etc. The second course  14  is similarly constructed, beginning from the upper left segment of the wall  10  with a vertical block  90 , three stacked  30 C blocks, a vertical block  90 , and so on. Note that the first and second courses  12 ,  14  are shifted linearly with respect to each other along their top and bottom surfaces, respectively, by a distance of about one-half the width of a vertical block  90 . This configuration assures that vertical joints do not span adjacent courses. This not only strengthens the retaining wall but also allows the blocks to be arranged in a more random fashion. Note that even though the first and second courses  12 ,  14  are arranged to present a more or less planar viewable surface, an extremely large number of combinations of blocks are possible, limited only by the imagination of a designer or an assembler. As a further note, while the viewable surfaces  34 ,  94  of the front members  32 ,  92  of the horizontal and vertical blocks  30 ,  90 , respectively, are depicted as being roughened, it is understood that blocks having other surface finishes and textures may be used. 
   Referring now to  FIGS. 2 and 3 , each horizontal, preformed block  30  includes a front member  32 , a rear member  42 , opposing sides  44   a ,  46   a , a top  50  and a bottom  60 . The front member  32  includes a viewable surface  34  having a predetermined texture and finish. As mentioned above, it is understood that the viewable surface  34  may be provided with other textures and finishes, as desired. The front member  32  also includes a rearwardly facing back surface  36  in spaced relation from the viewable surface  34 , with the back surface  36  including stop surfaces  38 ,  40 . As will be discussed later, the stop surfaces  38 ,  40  enable adjacent courses of blocks to be operatively connected to each other. 
   For purposes of this application, the term operatively connect is understood mean that movement between adjacent courses of blocks in response to pressure exerted by retained material and water is resisted by complimentary confronting surfaces in adjacent courses of blocks. 
   Referring again to  FIGS. 2 and 3 , each horizontal block includes a rear member  42  having opposing sides  44   b ,  46   b , interior surfaces  48   a , an exterior surface  48   b , a top  50 , and a bottom  60 . Rear member  42  is held in spaced relation from the front member  32  by a web  74 . The web  74  includes opposing sides  76 ,  78 , an upper surface  80  and a lower surface  82 . With regard to  FIG. 2 , the top  50  of the block includes top support surfaces  52 ,  54  that are configured to operatively contact bottom support surfaces  62 ,  64  of overlying courses of blocks (See,  FIGS. 6–9 ). The top  50  of the block  30  also includes a recess  56  that extends downwardly from the upper surface  80  of the web  74 , and downwardly relative to the top support surfaces  52 ,  54 . The recess  56  includes a stop surface  58  that is in alignment with the stop surfaces  38 ,  40  of the back surface  36  of the block  30 . Together, these stop surfaces  38 ,  40  and  56 , extend substantially along the entire width of the block  30  and greatly expand the operative connection range available to a practitioner. Preferably, the stop surfaces  38 ,  40 , and  58  will be located a certain, fixed distance measured from a feature common to all of the blocks, such as the viewable surface  34 . The bottom  60  of the block  30  includes corresponding bottom support surfaces  62 ,  64  that are configured to operatively contact top support surfaces of underlying courses of blocks (See,  FIGS. 6–9 ). The bottom  60  of the block  30  includes a projection  66  that constitutes the other part of the operative connection between adjacent courses of blocks. The projection  66  extends downwardly from the lower surface  82  of the web  74  and downwardly relative to the bottom support surfaces  62 ,  64 . The projection  66  includes an indexing surface  68  that is configured to operatively contact the stop surface(s) of an adjacent course of blocks. As will be described later in greater detail, the indexing surface  68  differs from the stop surfaces in that there are a plurality of fixed distances measured from a feature common to all of the blocks, such as the viewable surface  34 , at which an indexing surface  68  may be located. 
   As described previously, and as shown in the  FIG. 1 , the thickness of block  30  may be formed incrementally. That is, the horizontal blocks may be formed in such a manner to allow stacked blocks  30  to be equal in height to a vertical block  90 . And, while the incremental units chosen may be quite small, the preferred incremental thicknesses are approximately one-third, one-half, and two-thirds of the height of a vertical block  90 . For example, the horizontal blocks may have incremental thicknesses of one, two and three units, while the vertical preformed block is three units tall. Thus, the horizontal blocks may be stacked in whatever units which, when added together, would be three units tall. 
   Referring now to  FIGS. 4 and 5 , each vertical, preformed block  90  includes a front member  92 , a rear member  100 , opposing sides  102 ,  104 , a top  110  and a bottom  120 . The front member  92  includes a viewable surface  94  having a predetermined texture and finish. However, it is understood that the viewable surface  94  may be provided with other textures and finishes, as desired. The front member  92  also includes a rearwardly facing portion  96  in spaced relation from the viewable surface  94 , with the rearwardly facing portion  96  including a stop surface  98 . As will be discussed later, the stop surface  98  enables adjacent courses of blocks to be operatively connected to each other. 
   For purposes of this application, the term operatively connect is understood mean that movement between adjacent courses of blocks in response to pressure exerted by retained material and water is resisted by complimentary confronting surfaces in adjacent courses of blocks. 
   Referring again to  FIGS. 4 and 5 , each vertical block  90  includes a rear member  100  that is held in spaced relation from the front member  92  by upper and lower webs  106 ,  108 , respectively, and opposing sides  102 ,  104 . With regard to  FIG. 4 , the top  110  of the block  90  includes top support surfaces  112 ,  114  that are configured to operatively contact bottom support surfaces of overlying courses of blocks (See,  FIGS. 6–9 ). The top  110  of the block  90  also includes a recess  116  that extends downwardly relative to the top support surfaces  112 ,  114  and which includes a stop surface  118  that is coincident with the stop surface  98  of the rearwardly facing portion  96 . As can be seen in  FIGS. 4 and 5 , the stop surface  98  (or alternatively  118  in this particular instance) extends along the entire width of the block  90 . Preferably, the stop surface  98  will be located a certain, fixed distance measured from a feature common to all of the blocks, such as the viewable surface  94 . The bottom  120  of the block  90  includes corresponding bottom support surfaces  122 ,  124  that are configured to operatively contact top support surfaces of underlying courses of blocks (See,  FIGS. 6–9 ). The bottom  120  of the block  90  includes a projection  126  that constitutes the other part of the operative connection between adjacent courses of blocks. The projection  126  also extends downwardly relative to the bottom support surfaces  122 ,  124  and includes an indexing surface  128  that is configured to operatively contact the stop surface(s) of an adjacent course of blocks. As will be described later in greater detail, the indexing surface  128  differs from the stop surface in that there are a plurality of fixed distances measured from a feature common to all of the blocks, such as the viewable surface  94 , at which an indexing surface  128  may be located. 
   As described previously, and as shown in the  FIG. 1 , the height of the vertical block  90  is based upon an incremental unit, such as the thickness of the thinnest horizontal block. 
   Before describing  FIGS. 6 ,  7  and  8  in detail, it should be understood that the operative connection between vertical and horizontal blocks is essentially the same and the blocks depicted in  FIGS. 6 ,  7 , and  8  could be any combination of horizontal and vertical blocks. For purposes of simplification, however, the blocks shown in  FIGS. 6–9  will be identified and described with the convention that each upper course block is a vertical block  90  and each lower course block is a horizontal block  30 . Using the aforementioned convention, the operative connections between adjacent courses of vertical blocks as depicted in  FIGS. 6 ,  7  and  8 , will now be discussed. 
     FIG. 6  illustrates an operative connection in which a viewable surface  94  of vertical block  90  is offset from a viewable surface  34  of a horizontal block  30  by a first predetermined distance  16 . As can be seen, the bottom support surfaces  122 ,  124  of the vertical block  90  are in substantial contact with the top support surfaces  52 ,  54  of the horizontal block  30 , and the indexing surface  128  of the projection  126  of vertical block  90  is in substantial contact with the stop surface ( 38 ,  40 ,  58 ) of the back surface  36  and/or recess  56  of the horizontal block  30 . 
     FIG. 7  illustrates an operative connection in which a viewable surface  94  of vertical block  90  is offset from a viewable surface  34  of a horizontal block  30  by a second predetermined distance  18 . And,  FIG. 8  illustrates an operative connection in which a viewable surface  94  of vertical block  90  is coplanar with a viewable surface  34  of a horizontal block  30 . It should be noted that the recesses depicted in the aforementioned  FIG. 6 ,  7 , and  8  are configured to be sufficiently large enough to accommodate projections of varying sizes, and the only surfaces at which a contacting relation must be established in order to operatively connect or restrain adjacent courses of blocks so that they are able to resist forces exerted by retained material are the stop and indexing surfaces of the recesses and projections, respectively. 
     FIG. 9  illustrates an embodiment in which a plurality of horizontal blocks having different incremental thicknesses are operatively connected to each other in a plurality of stacked relations, or groups. As described previously, and as shown in the  FIGS. 1 and 9 , the thickness of horizontal block  30  may be formed incrementally to allow stacked horizontal blocks  30  to be equal in height to a vertical block  90 . For example, a preferred horizontal block  30  incremental thickness of one, two and three units with approximately one-third, one-half, and two-thirds of the height of a vertical block  90  is shown in  FIG. 9  by horizontal blocks  30 C,  30 B and  30 C respectively. 
   Further shown in  FIG. 9  are the viewable surfaces of the two lowermost horizontal blocks  30 A,  30 C that are offset from each other by a first predetermined distance  16 . The viewable surfaces of the second and third horizontal blocks  30 C,  30 B are offset from each other by a second predetermined distance  18 , and the viewable surfaces of the two uppermost horizontal blocks  30 B,  30 B are coplanar. 
     FIG. 10  illustrates an embodiment in which a retaining wall includes a plurality of blocks, some of which have been setback. Beginning with left side, there are two horizontal blocks  30 B,  30 B that are stacked one above the other in a group, with the upper block  30 B set back from the lower block  30 B a predetermined distance. Next, there are two horizontal blocks  30 A,  30 C that are stacked one above the other in another group, with the upper block  30 A set back from the lower block  30 A a predetermined distance. Next, there is a vertical block  90  that is set back a predetermined distance. And finally, there is a horizontal block  30 A. Thus, the lowermost horizontal blocks of this embodiment are in alignment with each other, while the uppermost horizontal blocks and the vertical blocks are in alignment with each other. Note that the course as depicted is equal to the height of the vertical block. More importantly, with this invention it is possible to have setbacks between adjacent stacked and/or vertical blocks within each course. Thus the possible arrangement of blocks is greatly increased to provide a nearly limitless variety of configurations available to a practitioner. 
   Shown in  FIG. 11  is a retaining wall embodiment where a plurality of horizontal preformed blocks  30  are stacked one above the other in a columnar fashion  130 . One block  30  in one course is positioned directly over another block  30  in an underlying course. Blocks  30  stacked in a columnar fashion  130  may also be positioned in one course in a predetermined relation with blocks  30  in an adjacent course as the indexing  68  and stop surfaces  62 ,  64  of adjacent courses of blocks  30  are brought into registry with each other. Another predetermined relation for positioning the blocks  30  is a setback wall in which one block is offset a first predetermined distance from another such that the wall has a constant upwardly receding slope or batter. A third type of predetermined relation for positioning the blocks contemplated by the invention is a setback with a variable upwardly receding slope in which a plurality of predetermined distances is used to offset one block from another. 
   Blocks  30  stacked in a columnar fashion  130  of the present invention provide the advantage of allowing the viewable surface  34  of a horizontal block  30  to be positioned in a variety of predetermined relations to another viewable surface  34  of another block  30 . Blocks  30  stacked in a columnar fashion  130  may be positioned in a coplanar relation to another viewable surface  34 . A coplanar relationship between the viewable surfaces  34  of horizontal blocks  30  can be understood by modifying  FIG. 8  such that the vertical block  90  is replaced by another horizontal block  30 . Similarly, by replacing the vertical block  90  with another horizontal block  30  in  FIGS. 6 and 7 , one can appreciate two other types of viewable surface relations made possible by blocks  30  stacked in a columnar fashion  130 . The distance between the viewable surface  34  of lower block  30  from the viewable surface  34  of the upper block  30  is shown by a first predetermined distance  16 . Thirdly, in a setback retaining wall with columnar stacks  130 , horizontal blocks  30  of the present invention may be offset from each other by a plurality of predetermined distances. A modification of  FIG. 7  would show the difference between the two viewable surfaces  34  of the two horizontal blocks  30  as a predetermined distance  18 . 
     FIG. 12  illustrates an embodiment of a running bond  140  type of stacked retaining wall of the present invention. The same advantages provided by the invention to a columnar stacked retaining wall  10  are also provided for a running bond  140  stack of horizontal blocks  30 . The indexing  68  and stop surfaces  62 ,  64  may be used to position blocks  30  in one course into a predetermined relation with blocks  30  of an adjacent course. In a running bond  140  stack of blocks  30 , the viewable surfaces  34  of the blocks  30  in one course may be positioned into a predetermined relation with blocks  30  of an adjacent course as the indexing  68  and stop surfaces  62 ,  64  of the adjacent course of blocks  30  are brought into registry with each other. Both the blocks  30 , and the viewable surfaces  34  of the blocks  30 , respectively, may be positioned in a predetermined relation with each other in a running bond  140  retaining wall  10 . In a running bond  140  retaining wall  10 , blocks with a plurality of predetermined distances may be positioned in a coplanar relation, a constant batter relation, or a variable batter relation. 
   A significant advantage to the present invention can be seen in  FIG. 12  with a running bond  140  stacked retaining wall. A recess in preexisting blocks offered limited width, which consequently limited the placement options of the horizontal blocks  30  laterally along the course of the wall. The present invention recess  56  extends continuously and completely through the block  30 . Now a block in a running bond pattern may be moved laterally as much as desired in either direction, providing more options and patterns. 
   The present invention having thus been described, other modifications, alterations or substitutions may present themselves to those skilled in the art, all of which are within the spirit and scope of the present invention. It is therefore intended that the present invention be limited in scope only by the claims attached below:

Summary:
A retaining wall with a series of differently sized, pre-formed blocks. Each block includes a projection and a recess, with the projection and recess arranged and configured so that each projection effectively engages a recess in an adjacent course to connect and align adjacent courses in registry. Retaining walls made of horizontal blocks may be stacked in columnar fashion or running bond fashion. The location of the indexing surface on a projection relative to the viewable surface of the block may be varied to enable adjacent courses to be coplanar or tiered in a variety of predetermined offset distances.